I would be happy with James Daniel from Howard, so for me it isn't just that Alstork is coming from a low-major conference --- it's more about his game and concerns about how it translates at a PowerConference level.
My main point with Alstork, is the inverse to your statement --- just because Alstork was productive at a low-major level doesn't mean he will be able to be similarly productive at a PowerConference level.
Yes there are instances of players from low-major or mid-major programs moving up to the PowerConference ranks and being successful. But there are elements that helped those players make the jump --- Duncan Robinson is a 6-8 shooter with NBA-plus 3-pt range; no matter what level he's playing if you don't extend out to him, he can hit 3s. Others have extreme quickness. Some were Europeans/Australians who didn't get recruited overseas. Others are players who learned to be extremely efficient during their first 3/4 years in college.
With Alstork I see a guy who is a better athlete than most of his competition in the Horizon League and that's why he's productive (w/o being efficient). But I don't think he'll be a better athlete than most of his competition in the B1G........ so what's his niche that allows him to produce if he comes to Michigan?