That wasn't the call though. It was unsportsmanlike conduct on both teams.
It wasn't? Do you know that for a fact? In the replays you can see the flag fly straight up in the air from the sideline right after Skow makes the catch.
Refs don't always get calls 100% correct. The call on the field may have been unsportsmanlike, but should have been illegal formation if Skow did not check in.
After the referees conferred, they may have asked the head linesman if Skow checked in. The HL may have been looking elsewhere like counting the players on the field (that is part of their job). Skow probably came over and told the ref crew hey I checked in and the HL wasn't paying attention.
I never saw a second flag, so maybe the refs called offsetting unsportsmanlike penalties for a do-over. Some referees are more concerned with being right than getting the call right. This is what happened yesterday.