Yes, of course. You don't think Mongoose would let us get away with something as obvious as getting a cheaper, unsuppressable unit by using True Believers to compensate for the disadvantages of the troops being civilians?
Though, still, if you upgrade to true believers, you get part of the cost back by making them civilians. The remaining disadvantage to the civilians is that the RPG will shoot poorly, but in a squad with lots of riflemen and only one RPGer it could pay off. Though, large squads usually don't get suppressed in the first place.