Good thing that it went to Wine I guess, as they do lots of work to get old Windows programs up and running in Linux and that often involves Mono.
I see this as the main purpose of this transfer of ownership. When it comes to developing new software, MS has their modern tech stack for creating cross-compatible code, and the recommendation is to use that. But that is not helpful when trying to get old legacy software running on a modern system. So MS is giving this “outdated” technology to the WINE team. A team whose primary goal is getting incompatible software to run in the “wrong” environment. This should allow WINE to continue to properly handle older Mono software for the foreseeable future.