[Xperia Z2 Tablet Q&A, Help & Troubleshooting] Elliander:
Correction! It all works!

EDIT: I backed up everything with Titanium Backup (and moved the backup to SD and removed the SD to be safe) and then performed a factory reset. (The APN settings will be wiped, so to anyone reading this: Don't freak out if your mobile data plan doesn't seem to work.) and then performed an Easy Root and this one is looking MUCH cleaner:

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= =
= Easy Root Tool v11 =
= Supports various Xperia devices =
= created by zxz0O0 =
= =
= http://xdaforums.com/ =
= showthread.php?p=53448680 =
= =
= Many thanks to: =
= - [NUT] =
= - geohot =
= - MohammadAG =
= - cubeundcube =
= - nhnt11 =
= - xsacha =
= =
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Waiting for Device, connect USB cable now...
Make sure you have only one Android device connected
BlueStacks emulator can also cause problems
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Device found

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Getting device variables
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Device model is SGP561
Firmware is 17.1.D.0.417

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Sending files
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35 KB/s (1585 bytes in 0.044s)
3608 KB/s (657704 bytes in 0.178s)
158 KB/s (1133 bytes in 0.007s)
99 KB/s (9496 bytes in 0.093s)
580 KB/s (13672 bytes in 0.023s)

Copying kernel module...
647 KB/s (34473 bytes in 0.052s)
46 KB/s (767 bytes in 0.016s)
948 KB/s (13592 bytes in 0.014s)
Kernel version is 3.4.0-perf-g31245c3
Version does not match 3.4.0-perf-ge4322cd, needs patching...
1+0 records in
0+1 records out
19 bytes transferred in 0.001 secs (19000 bytes/sec)
Kernel module patched.

modulecrcpatch (by zxz0O0)

module_layout: patched to 0xCFADE050
__aeabi_unwind_cpp_pr1: match
kallsyms_lookup_name: not found
printk: not found
mem_text_write_kernel_word: not found
__aeabi_unwind_cpp_pr0: match
successfully patched

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Loading towelzxperia
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698 KB/s (13592 bytes in 0.019s)
2639 KB/s (197320 bytes in 0.073s)
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Waiting for towelzxperia to exploit...

towelzxperia by zxz0O0 (EasyRootTool Version)
libexploit by geohot

libzxploit.so created
doing the magic
creating vm (loljavasucks)
mount: Operation not permitted
cleaning up
done

Checking if device is rooted...

Device rooted.

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Checking for Sony RIC
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Sony RIC Service found.
Installing RIC kill script installmount.sh...
Stock mount does not exist. Creating dir and link
Installing of mount.sh finished

Done. You can now unplug your device.
Enjoy root
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What to do next?
- Donate to the people involved
- Install SuperSU by Chainfire
- Install dualrecovery by [NUT]
- Backup TA partition

Press any key to continue . . .

I then had absolutely NO problems with TA-backup and was able to run adbd-insecure (which I couldn't before) and was able to successfully create the TA.img file for my DRM keys (which I also couldn't before).

I then had no problems editing Platform.XML to restore SD card access, and I have no problems creating folders in the root and moving files into it (although moving very large files to a folder in the root seems to cause the tablet to freeze up and reboot a few minutes later, which bites because I am trying to get Ubuntu. I'm going to have to go with a smaller image.)

Finally, I was able to restore all of my settings and app data without difficulty with Titanium Backup *AND* I was able to freeze or delete the system apps I so hated! (Unfortunately, even after enabling SD write access, Titanium Backup is oddly unable to write to SD. I had to manually copy the backup folder from SD back to internal and then reboot before I could even restore the backups as well. I thought that was very strange. Especially since I have a Pro version.)

Conclusion: The problems I went through were largely related to all of the failed rooting attempts. Don't try anything EXCEPT "Easy Root". It's all you need, and if you start with it you shouldn't have any problems. If you have the problems I had, you will have to do a factory reset before you can fully root the device.

As a side note, it needs to be mentioned that the Xperia Z2 tablet has a "Rooting Status" flag which is a permanent trigger. Even after a factory reset without root the flag remains triggered. If you are concerned about warranty you should be aware of it. Also, after I performed the factory reset I was unable to get rid of the Verizon "Tablet Activation" message permanently. I didn't have it before, but now I have it.