Well you say that but it would take a massive Tory MP extinction before they NEED him to vote. He also seems to be deeply unpopular esp with Sunak who seemingly deliberate ignored him the other day. I think the Tories are of the opinion he's a bit Toxic
When Mad Nad went on the same programme, she had the whip removed and in reality was only allowed back in the party because, as you say, they needed her votes and they needed her to shut up (She was proposing a joint Tory / UKIP slate at the next election)
Mancock doesn't have the luxury of having anything the Tories need, he also seems to have his constituency party angered. The Tories may decide they desire his very safe seat more than they desire him filling it.