No one should be allowed to queue without a soul stone if applicable.

[Iscah]

On a technical level job stones are considered equipment, and equipment is validated before you queue. That's why you can't queue for something where your ilevel is too low.

Hmm, I wonder if it's possible to assign job stones a scaling ilevel like the aetheryte earring? It would keep pace with your current level, but not having one would severely impact your average gear level.