Hey Ghosty!
Well, its not an official rule that the CTs must have mics. If a small number of the CTs don't it usually doesn't matter.
However, it is a rule that only orders given over the mic are valid.
Thus if only two have mics, and those two die, the CT's will not be able to give orders, which isn't good.
If this comes up, nicely ask the CTs without mics to switch to T to give the people with mics a chance to play ct.
If they refuse, let one of the admins know, and they'll handle things!
See you in jail soon!
-Crazyrockets