You can throw grenades, but if you spam it you will be kicked. You will get warning if you are reaching a configurable limit per life, limit reset every time you respawn.
Configuration
-- Maximum grenade a player resupply before getting warned
self.MaxGrenadeBeforeWarn = 2
-- Maximum grenade a player resupply before getting kicked
self.MaxGrenadePerLife = 4
well, at least you can throw nades if you continuously got killed. Your team tickets will go down if you keep suicide anyways, lesser impact for normal gameplay.