Sigh and sell off the Working Rat
From Fallen London Wiki
This page contains details about Fallen London Actions.
From: Sartorial squeamishness
You can't afford to keep companions who complain about your working methods.
"It wasn't my place to speak. I see that now."
He doesn't want to be sold on, but it's not up to him. You show off his workmanship and don't let the purchaser meet him in advance. Your strategy works, and your rat is off to repair machinery at Mrs Plenty's Carnival.