I think much of this is precipitated by the naive idea that we believe the variant JUST has begun spreading across the US. The fact is we're far behind the rest of the world with regard to sequencing of the virus from positive tests. Ignorance is bliss, right? I believe it's far more likely that this variant has been in areas of the country for some time, we just weren't aware. Now that (at the least it appears University of Michigan) is sequencing I think you'll find far more. It doesn't necessarily mean that it's a new occurrence needing the implementation of extreme measures.
Also note the language in the UM press release: "...the University of Michigan Athletic Department will immediately pause athletic activities in all sports, including games, team and individual training sessions, until further notice and up to 14 days." It doesn't say it's definitely 14 days, but up to, so there leaves the possibility that it could end early. I suspect the reason for that statement is this:
https://twitter.com/ethan_sears/status/1353171434898661381?s=20
Beyond the confirmed variant cases they are presuming 15 other positives from the week are also the variant. This feels like an "out of an abundance of caution" type action. If those 15 cases aren't the new variant, does this change the timetable of the pause? Logic would make one say yes, but given everything to date, who knows.