This doesn’t make sense. The only appeal of Catalyst to me is that it makes bringing an iOS app not present on the Mac to the Mac easier. You could argue that it’s good for maintenance purposes where instead of worrying about two separate things, you only put your time into one thing. True, but that doesn’t apply here — Apple is a trillion-dollar company, not a nameless bunch of hackers who want to heat people with microwaves.
The only reason Apple is doing this (if it is, of course) is to have another proof of concept for Catalyst.