At this risk of sounding all philosophical, the moment he knows that bet exists is his decision not rigging it one way or the other anyway? (I know the odds were obviously favourable in one direction).
It's the kind of stupid bet companies put on to look like they're kings of banter so they should take the hit. Though I guess the coverage alone is worth more than the "five figure sum" it's costing them and they seem proud enough to shout about it.
And if it's "caught on camera eating a pie" then there's surely no way to guarantee that the BBC would see it or be interested in it, unless the cameraman or the director need to be under investigation too. That would've been my defence at least