While using !friendly (thanks for the fix by the way) as a scout, one could be able to jump several times in the air as if under the effects of soda popper or Atomizer. It seems that now the scout while !friendly will take damage from those jump as if normal playing and dying.
Engi is also able to to the gunslinger taunt, which is able to taunt the enemy (without killing them though). Could result annoying (even if difficult to excecute) to many.
Medics from the same team as the !friendly player can heal said !friendly, gaining uber from them.
!friendly players are affected by Loose Cannon's Knockback (could mean that soldier could get rage from !friendly players as well)