That's the immediate result. But what about later, when the war is over? Military expense is non-productive, economically it's the same as just giving people money for free while they are sitting on the couch (nobody is killed in the latter case though).

Military overspending literally killed Soviet Union, and people returning from Afghanistan war made guaranteed the unforgettable social climate after that. I don't see any reason to be bullish on Russia, even if Trump now gives up Ukraine for Putin.