It could be a positive thing to an extent. JTAC training has to be phased, in the same way that flying training is. So at the end of the training, you need a pair of jets with pods, working ROVER capability, LTM at night, etc etc. You need to finish your training working with the aircraft you'll actually control for real, using realistic target sets and realistic concerns.
However, when it comes to the first stages, just talking to the aircraft, managing deconfliction, and doing talk-ons to help get eyes on, there's no harm at all in using a Tucano and it strikes me as a very smart move.
Your Tucano, flown by an ex-GR4 pilot, can stay on task for ages, and there are loads of them. No advanced capability, but the ideal training mule to allow a JTAC to practice controlling aircraft and airspace for real. Hard work for the crews to simulate having the appropriate kit to punch coordinates into, but a lot of the concepts are still valid.
Ideal stepping-stone to the Hawk and then Tornado, and a sensible use of under-used assets now that student numbers are lower? The
PR fluff piece is a bit silly, as it's obviously never going to replace a Tornado and I can't imagine for a second how it'll imitate a Reaper in any way, but still a smart move.