They say “the only US alternative”, which is true, but it’s not the only alternative - nasa paid for seats on Soyuz for many years, and I’m sure they could go back to doing the same. Perhaps China would be willing to sell seats on their launches. Maybe India will be in a position to offer human launches to the U.S. fairly soon - should be up and running by 2027, and they seem to hit their objectives most of the time.

Cooperation with roscosmos seems to have been largely unimpeded by Russia’s political and military actions over the years, so these all seem like realistic possibilities.

Yes, it will be a shame if the U.S. has no launch capability of their own, but short term partisan political thinking is much more important to the electorate than long term national strategic interest.