I simply don't think it's a move related to money, or at least not directly related to money.
I open the play store less than once a month, if they remove fdroid I guess I'll open it twice a month? How much money can they make for the 2 rows of sponsored apps they show me (which I don't tap anyway) in the 30 seconds necessary to find an app and press install?
People installing apks outside the play store are already a minority. Beside myself I think I know 1 person who may be using fdroid, maybe 2
I guess it could be a really dumb monetary choice? You never know with corporations