voted up. when using grenades, it takes both hands, and much more that 2 seconds.
-you take it out i.e. remove it from the pouch,
-undo all the safeties (depending on what grenade, this is the future who knows what new safety rules will be in place)
-tell everyone you're throwing a grenade
-throw the grenade.

Grenades should at least have to be selected as a weapon like in Battlefield 2. There is no way a professional soldier will pull out and lob a frag grenade with his left hand if he is right handed, whilst holding his gun in his right hand, in 2 seconds.