If one confederate dodges and is chastised for it, I really don't know what to expect. If I had to guess, I'd guess that standard Asch rules apply and the effect of the local group's pressure goes out the window

That's not the normal Asch setup- the dissenter isn't ridiculed for it; the subject feels free to dissent because they've seen someone else dissent and 'get away with it'. I would expect that the chastistement variation on any Asch test would produce even more, rather than less, conformity.