You make an obvious but important point 2 Sheds.
In my opinion an A/G Operator would be more likely to cause a problem by passing an instruction than help matters.
Pilots do generally know what they are doing, and are reasonably situationally aware. In a critical moment, to pass an instruction when providing a Radio service, could cause confusion. Pilots can reasonably expect only to receive information, or at the very most passed clearances from a different authority.
It is also worth noting that an A/G Operator not being trained or qualified to issue instructions would not necessarily make the best decision in the time, no matter how good naturedly they made that decision.
I would much rather pass accurate and useful information briefly than have to explain myself in the Ops Room or Court. Ultimately, I don't have the training to ensure that a breach of the rules would actually diminish the risk of accident
Phil