Except that the strategy I mentioned wouldn't just be a simple 'disable all crossplay' functionality, what I suggested is that SIE could announce publicly (or privately to publishers) that from now on, all online games in Playstation's ecosystem can only have crossplay enabled with PC and Nintendo consoles, which would then place the onus on the 3rd party publishers to choose between having their games enable crossplay for Playstation + PC + Nintendo, or Xbox + PC + Nintendo.
Sure, Minecraft would have crossplay with Playstation disabled but that wouldn't be a surprise since Minecraft is already a 1st party Microsoft owned franchise, so the real question would be what the other publishers would decide to do for their online games that have console crossplay enabled. As of now, I'd find it very plausible that those other publishers would opt to go for the Playstation + PC + Nintendo combo for crossplay, as that would give those games a higher userbase, and then the Xbox online gaming communities would be left out in the cold, resulting in lower online population for their multiplayer games, and longer search times to find matches.
If SIE does decide to go down this route with blocking crossplay with Xbox, then I think that would help bolster the perception among the general gaming population that Playstation provides the better online experience for multiplatform online multiplayer games, and helps further drives Playstation console market share upward relative to Xbox. Again, this strategy would take an iron heart to do, but I think Jim Ryan is a ruthless business executive who feels that he is under no obligation to help assist Xbox at all.