Why did they bother polling Matheson after the primaries?
Maybe in hopes that Matheson could pull an Evan Bayh and enter the race late? Not sure what Utah's laws are regarding that, but perhaps Dems could convince Snow to drop the senate race and have Matheson as the replacement. Highly unlikely to happen though, and I still think Lee would beat Matheson.
That's the only reason I could think of as to why they are still polling Matheson even after the primaries. That, or maybe the pollsters were just simply curious as to what that potential matchup would look like in a time where Trump is very unpopular in Utah.