But I would argue that motivating through fear isn't even relevant to this situation. Is making death threats in order to convince somebody to stop doing something a valid way to motivate through fear? Is cursing somebody out on a mailing list really all that terrifying? If it is, is that the reason Linus, for instance, does it?
I think the answer to all of these is no.
Further, it may be appropriate to shame racists, homophobes or sexists into changing their ways (or, I would argue, just not espousing their views publicly). But is it really appropriate to do this, to this extent especially, to programmers who wrote bad code?
Programming relies on rational, careful cognitive consideration of problems. That's the opposite of what fear inspires. Fear-based "motivation" is lousy in general, and doubly lousy for open source software.