Unintentional teamhits don't justify a ban in any case. Yes, 3 teamkills in one round is bad and he should probably watch his aim more carefully, but from what i've seen here in this thread there is absolutely no evidence that those tks were intentional.
Denied.
PS: Expect some warnings for your posts. This is the ban-forum, so please follow the rules for it:
http://forum.melee.org/eu-%28official%29/ban-section-rules-no-spam/