I think some folks have missed several points: 

1.  After his initial tweet, he posted another tweet that just said "I apologize". 
2. Terry followed up with a lengthy explanation that it was an "emotional moment", apparently equating something about his dad and the Japanese he fought.  While I didn't see the original tweet, apparently there was a mention of HIS BOOK in the apology which he got called out on.  

Various people I know have said that his follow up apology was worse than his original tweet.    I wasn't angry but just posted to Terry saying "I hope you get help.  Sounds like you have issues to address and I hope it doesn't carry over to real life".  

Dude made a big mistake in public and he paid a price for it.   It's the way things are in 2017.