You are possibly correct. No more than possibly. The reverse exhaust would have been cancelled immediately. What got them was that the engine debris blew out a fuel tank access panel leaving a solid column of fuel about 8 inches wide pouring out onto the ground and into a hot exhaust. the fire was blowing directly onto the fuselage (by the wind) and the burning pool of fuel spread under the aeroplane. With respect, I think the effect of the reverser air was marginal.
The point of it all is: the crosswind effect is extremely critical. One side of the culprit engine itself can be unburnt, and the damage could easily be most severe on the other side of the aeroplane that didn't have the initial problem.
Unctious- very possibly they trailed fuel throughout flight and on taxi in- it may have been the stopping that undid them!