It would appear that you're trying to present the two narratives as mutually exclusive. One of the points Mearsheimer is making is that both of these narratives are simulatenously true and the west must appreciate the geopolitics in play to enable foreign policy good enough to deal with this issue.
Besides the point, I'm not sure what any of this has to do with entropyneur's claim that NATO expanding is a "russian propaganda".
Reality: Countries wants to join NATO, the defensive alliance, because Russia repeatedly invades countries.
NATO has expanded because of Russia's invasion of Ukraine, and neither Finland nor Sweden would've joined if Russia didn't attack Ukraine.