Okay, I think I need to make clear why I think this is a good idea. The reasons for and against having the BP townie claim are these (I hope I didn't forget anything:
CONTRA claiming:
1. mafia knows the exact setup
2. mafia won't waste a kill on the BP townie
3. mafia won't roleblock the BP townie
PRO claiming:
1. the BP townie essentially turns into an IC
2. our lynch pool gets smaller, giving us a bigger chance to hit mafia
3. we know more about the setup (there is a Jailkeeper or a Tracker)
4. our PR's target pool gets smaller
So regarding the contra points:
1. yes, they do. What harm is that, exactly? They have an information advantage already, they will have an information advantage afterwards. And it's not like they can use that information for fake-claims, because one of us knows the exact setup as well.
2. probably the biggest downside to BP claiming. But I think it is outweighed by the upsides. And there's a 50% chance we still have another protective role.
3. okay, mafia chances of succesful roleblocking increase from 1/7 to 1/6. That's a risk I'm willing to take.
What it really boils down to is this: Do we think that one-shot BP IC is a more powerful role than one-shot BP townie? Imagine Voltgloss in M31 would have been one-shot BP instead of IC. Imagine Galzria in M32 would have been one-shot BP instead of IC. Would this have increased town's chances of winning in those games? I don't think so. And both didn't even have the additional bulletproof we would have.