Obvously the issue isn't Marks, but filling the last roster slots. I'm very curious about why the Suns were trying to trade up to get Strawberry only to give the slot to Marks - because they clearly need a better big than Marks on the deep bench.
When the Suns run a big lineup with Amare and KT, it means the biggest guy they have coming off the bench is Diaw who is not able to defend the low block. In a series like against the Spurs, this presents a huge problem if the best of the rest is Marks. I don't know if there is a real low post defender out there available for at vet minimum, but I'd rather go through the search than to settle for Marks.
I could see giving Marks a "make good" contract to get him into camp. But if signing him means giving him a guaranteed contract, I just don't get it. There is simply no evidence that he can play, so why tie up a roster slot like that?
So far no one can give a logical reason for him taking up a roster slot, but it looks like that is exactly what is going to happen.