Yeah, I don't think MS treats indies anywhere near as poorly as they did in the 360 XBLA days. I'm not even sure any of the people Blow or Team Meat worked with are at MS anymore.The way MS treats indies is nothing like it was during the 360 days, I work with indie devs with some fellow streamers and we've heard nothing but good things about Chris Charla and his ID@Xbox team.
Despite this game not coming to XB1, XB1 gets a ton of indie games. Hell there's like 6-7 this week alone.
Most likely this developer is prioritizing the PS4/Steam version, then Switch and will then release it on XB1 later. Maybe towerfall sold worst on XB1 (due to coming way later most likely) so that is their right and that's ok.
(just quoted your post because it was continuing the previous conversation btw)
I think it really just comes down to devs having to prioritize ports and these days indie games sell better on PS4 and Nintendo platforms than XBO. All there is to it.