Can't come up with any; she seems pretty neutral about it, but I see how it could cause minor stress.
Mainly, she seems to know that that tub means feeding time (goes into hunt-mode in it even if there's no mouse to be seen) and it just seemed natural to keep reinforcing that. She was up for adoption bc of 'food aggression' and I just kept feeding her the way she was used to and the way I feed a couple of my cohabiting Thamnophis. May try feeding in-tank next feeding, see how it goes.
Haven't had time to do the forum thing for awhile, but I've actually never heard anyone present a strong case against feeding out of the tank, so I was interested. Your arguments make sense so IMO it's worth a shot.