In terms of the snipers being able to be resistant against mortar fire I completely disagree. Arty or tank rush is the prime method in which I lose my Ostheer snipers. You remove this option from the Soviet player what else have they got to do when this unit is in the hands of a good player?
If you believe your sniper will be targeted by in-direct fire it is time to be more conservative with it, keep it by itself to avoid it becoming collateral damage and aim to remove the in-direct fire threat. I personally have no problems with my sniper and get it the majority of my games.
In 2v2 there is nearly no room to do so. Your sniper is either shooting aka near the battle or standing far away aka useless. Most of the maps are so small (nearly all exp Moscow tbh) and concentration of deadly units and arty so high that you have no other choice: either use him and risk getting killed by one shell or let him in your base.