Good point! It's always fascinating when the sergeant at arms is actually employed since it's so seldom used. I'm sure Congress wouldn't go down that path with Trump for many many reasons, but perhaps it could be used against lower-level minions in extreme situations. Probably not, but fascinating to consider :)
It's a power they basically never use, but they can technically arrest someone for not complying with a congressional order/subpoena.
But then if they did decide to arrest Trump or others for compliance that'd pit the Sargent at arms directly against the secret services.