abs would most certainly help you in that situation. you can brake as hard as you want, and it will take you right to the point where front wheel lockup would occur, but keep it from happening. the only thing abs would do in your situation is keep the front from locking up, which with a flat rear tire, would still be a good thing.
You're right about not wanting the front wheel to lock up - that single disk on the heavy old Honda never did that anyway. I just wondered if the fork starting to rotate forward could trigger a release, lower the g-force. Probably not. I used a bad example. I've heard guys say they locked up the rear wheel to lay it down, but I've never needed, or wanted, to do that. I'd want abs at least on the front wheel on any bike if available.