I'm not sure what the licensing agreement currently is for the actual Game Maker, but even if there was an enforceable law for products made with it, it would only apply to that program itself.
Same goes for the exporter. The implied agreement only works for programs that are purchased from the Yoyo.
If there was no purchase, then there was no agreement.
Its a virtual Pandora's box. Yoyo put the box out there and somebody opened it.
Now they want them to close it even though that's an impossibility.
Frankly they should be looking at this differently, yes they will lose sales of their exporter, but now they will have an even larger market to sell Game Maker to.