OK, let's break it down:

In the position shown in Robi's diagram, Black (B) has the initial right of way because it is a leeward boat (Rule 11).

I think we all agree that B cannot lay the mark, even by luffing head to wind and coasting.

Red (R) can probably lay the mark by luffing and pinching.

R would need to avoid B if B tried to luff, but that's Rule 11, not Rule 18. B would be subject to the limitations of Rule 16 (Changing Course) and Rule 13 (While Tacking) if it went past head to wind.

B must tack (or gybe) to round the mark. Once they pass head to wind, Rule 13 kicks in and they must keep clear.

At that point, Rule 18.1(b) kicks in, which basically says that for boats on opposite tacks at a weather mark, Rule 18 does not apply.

B has two choices:
1) Luff hard and try to take R out (not my favorite, but hey, they're Lasers). This might be the only option if there's a lot of traffic immediately behind and there's no room to tack or gybe.
2) Slow down and tack as soon as it can clear R, or do a 270 degree gybe (again, they're Lasers and they spin on a dime), take the hitch out and tack back.

I prefer #2 since I would prefer to be at a keg after the races than in the protest room. The real lesson is to not let yourself get into that position in the first place if you can help it.