Both sniper rifles do 80 damage and I assume ignore armour so that's why they outright kill any target as long as the shot connects. In the grand scheme of snipers vs mortar shells, tank shells, flamers, and grenades, I don't think an extra 40 HP is going to matter much 99% of the time, but again, RNG. The extra armour on the Ostheer helps with moving away or retreating from small arms fire at least.
To the contrary, it would actually have significant impact. A mortar shell landing directly on a model does 80 damage and it does less damage with the AoE. Since the ostheer sniper only has 40hp, it is currently insta-dying to a mortar shell simply landing near him, not directly on top. A buff of another 40hp would significantly improve his survivability in this regard.
At the moment, the ostheer sniper simply requires so much babying (and praying to RNG gods) to be worth his cost the majority of the time, especially if the russian player gets 120mm mortar.