This was a crappy thing for UA to do.

But honestly, for MSP-SFO, DL is just the much better choice with something like seven daily nonstops and all mainline service (although UA is upgauging the route to twice daily mainline this summer). To me, the choice between a mainline nonstop and a connection through ORD is a no-brainer for the nonstop, regardless how nice the aircraft is on ORD-SFO.