The .22-250 would easily work on an AR10 platform with long bullets of course, if one thought they needed a semi-auto.
Again the point isn't to simply get something "into a semi auto" - the specific target audience is the folks who run the AR15 That's a huge audience, and a specific set of constraints. The ability to knock out two pins and do a significant caliber swap is the feature to work around, this does it.