Vikings: That's correct. Even if it's obvious that you won't be gammoned, a resignation will cost a gammon or even a backgammon unless a man's been taken off first.
frolind: I can see how that would be annoying in turn-based games. At Vog, where it's real-time, that sort of foolishness is rare (perhaps because it's more hassle asking for the resignation than it is to say no each time). I'm okay enough with the current way at the moment, though I'm concerned for those players who get caught out and lose points needlessly.
BBW I've slightly changed what I said in that post so it may not read as you originally saw, but the bit about avoiding backgammon by resigning a gammon wouldn't be the case. (Like you, I did think it might but it's more about losing more points than you should rather than fewer.)