TBH I don't really think the ability to use the tax payer MLE has much to do with this trade. For one thing the MLE is only worth 5.0 million, so its barely more than just a vet min salary under this new CBA. Also that presupposes that Grant is allowed to walk for nothing, and I'm not convinced yet that's going to be the case.
This could very easily just be an asset play. Move back six spots, pick up a few future seconds. That sort of trade happens all the time.