The Hadeans use both assault mortars and assault specials to prevent certain weapons (Medusa Mortar) being picked up by vehicles that shouldn't have them (Locust).
I would suggest not race-masking your powerups. That way, you avoid removing interesting tactics (such as stealing weapons).
Weapons
Moderators: GSH, VSMIT, Red Devil, Commando
Re: Weapons
Race masking comes into place with some more complicated situations. It is not something to use normally. One example might be to give the Swarm weapon crates that only they can use because crossing their weapons with other races would be game breaking.