The issue is not who it targets, but rather the fact that it invokes people with mental disabilities in an offensive, unkind, derisive, belittling and mean-spirited way as its vehicle for doing so.  It is distinguished from the redirects you refer by the note of ridicule, which is what makes it objectionable.  I directed your attention earlier to WP:USERPAGE#Inappropriate_content.  Please note that in accordance with this content guideline "[e]xtremely offensive material may be removed on sight by any editor."  I have elected not to do so, but another editor may come along and remove it and be well within his or her rights to do so without asking politely, as I do now for the third time, for you to remove it yourself.

Please be aware, however, that while polite requests are the preferred way of resolving problems with inappropriate userpage content, there are other avenues for doing so: as WP:USERPAGE#Removal_of_inappropriate_content states, user subpages with inappropriate content may be deleted through the WP:MfD process, in accordance with Wikipedia's deletion policy. (talk)