I don't know if mine would actually bite to protect me, but it's immaterial if they would. Not many people would try to go past three chows and a German shepherd, all barking and lunging (which is what they would do initially if someone threatened).
I am of the opinion that the therapy dog places should NOT accept dogs that have done bitework, and I'll tell you why. While those who have posted here may have done the bitework training correctly and maybe their dogs do have the control to not bite because they've been taught "off", there are too many out there who are not doing the training properly. I've personally seen this in dogs being trained for competition schutzhund. While it's a nice thought to say "dogs trained in schutzhund or PP are more trustworthy", unfortunately that does NOT follow through in all cases. I don't think that teaching a dog to bite and teaching it an "off" command necessarily creates a dog less likely to bite anyhow. It's less likely to bite when commanded not to, perhaps, but in all honesty giving a dog the right to bite can heighten the dog's desire to bite - not always, of course, but since bitework is typically a fun thing for the dog it can certainly make the dog more eager. Without the control of the owner at the time, it can transfer to a dog more willing to bite overall.
I'm not saying any of yours are - I don't know your dogs, and all we can go on here is what people say. However, I have seen it happen where the dogs are more unstable (in the sense of wanting physical contact with their mouths) afterwards. Since TDI and Delta Society have no way of knowing if the dogs "trained" in bitework have learned a higher inhibition or a lower one, it makes complete sense to me to make a rule that the dog can't have bitework training.
And personally I would prefer to see people be honest about this (again, not saying anyone is being dishonest). All it would take is one therapy dog biting someone and it being found out that the dog had a bitework background to discredit bitework training entirely and to discredit the therapy group too.
I think there's a very valid place for bitework training. I think there's a very valid place for therapy dogs. They don't need to mix and for practical, logical reasons.
Melanie and the gang in Alaska