Why is this forward firing rocket system viable for the V-280 but not the V-22?

Take a quick look at the picture above.  In it you see the troop transport of the V-280 being escorted by the gunship variant.

Simple question.

Why is this possible with the V-280 but not the V-22?  From what I gather the USMC will have "excess capacity" with regard to it's tilt rotor fleet with the last deliveries of the airplane happening next year. 

Have test been conducted using this type layout on it?  Is the USMC looking to retain troop carrying capability while laying down fires?

If so why?

A simple proposal would be to trial this solution (or something real similar) and if it works to designate one or two as deep escort tilt rotor platforms per squadron.

Rapid prototyping, testing, and experimentation is suppose to be the hallmark of how the Pentagon goes into the near future so why not try it out with the V-280 solution for forward firing gunship being trialed on the V-22.