If I was Richard E Grant...
...I'd go all-in on the fact that I’d been saying I wanted to be a Traitor before even entering the castle.
I’d say the whole thing, including seemingly mistakenly admitting that I WAS a Traitor after Claudia's selection, was part of my grand master plan. That I’d deliberately spent the entire pre-castle and selection period saying I wanted to be a Traitor because my actual plan was to go down as THE BEST FAITHFUL TRAITOR HUNTER EVER.
My plan?
To make the actual Traitors think I was one of them, in the hope that one of them would reveal themselves to me before the turret.
And you know what?
They did.
It was James Acaster.
James thought I was a Traitor, told me he was one, and then, after he went to the turret and realised I wasn't actually a Traitor, he got spooked and has been desperately trying to convince everyone I'm a Traitor ever since.
They banish James.
James is revealed as a Traitor.
I'm completely exonerated.
Until I inevitably mess it up again five minutes later.
It probably wouldn't work, and perhaps it'd break the Traitors' oath, but honestly, I think it's about the only way Richard could give himself even a small chance of escaping banishment after telling everyone he was one.