Oh you're absolutely right about that.
All I am saying is that they pushed an existing 1st party franchise to go multiplatform, which SDS (and to a greater extent, Sony) agreed to. When the rights were initially acquired, the MLB had to be aware that a 1st party studio is only going to make games for that platform. They made that franchise into one of the best annualized sports, MLB saw value in moving away from console exclusivity and wanted it multiplatform. The deal struck is pretty unique.
I understand your overall point that Sony is just as bad at exclusivity as Microsoft and agree. It ebbs and flows who is worse, but it is pretty naive of people to think one or the other cares more about the playerbase/community. I dont think its a coincidence you continually see "well, we didn't want to fracture the community!" said, then quickly followed up by noting that was really the only option possible.