Details

Recent event:

A player has been misbehaving in the server. This player's action has affected other players game experience and the overall the servers performance. Which is against the rule.
A player decided to votekick this offender. The offender left and rejoins the same server. The vote did not effect the offender.

My suggestion

Similar to current TF2 voting off player system. There should be a penalty if the offender left the server during an ongoing vote against them.
Also, the titan.tf rule book should mention this particular behavior