CirrusF,
My guess would be the FW community saying "We kill stuff" so send a fighter to do a fighters job. More likely, it's the RAF not wanting the AH64 to move onto yet more RAF turf.
From a tactics point of view, a helo is, IMHO, not the best platform to go after a light ac due to the lack of overtake if the intercept geometry isn't good. Much better would be a Tucano/PC-9 style ac, or, possibly ideal, would be an armed Agusta-Bell 609.
As Roust (sp?) proved, a light ac is a very difficult target to find and prosecute; they inherently have a low RCS and low IR signature so are ill suited to intercept by most FJ. However, if it can find it, a Typhoon-style would have no problems performing a VID / gun engagement as it is much more comfortable in the low speed regime than, say, a Tornado F3.