==> This issue has been fixed <==
For historical benefit:
On the user's page (SO, SF, meta, ...), if you type "T.J" (no trailing dot) in the search box you'll see names starting with "T.J" ("T.J. Crowder", "T.J. Boberek", "T.J.", etc.) but if you type "T.J." (with the trailing dot, as one normally would) nothing happens. At all. The currently-displayed results don't change (as opposed to showing no matches).
(Related but different bug: Users Search box doesn't find names with an apostrophe ')