So far, they haven't considered it.
It's however possible that it might not work anyway, if the seal for Joshua is possibly much stronger than the seal that the apple chink wanted to use on Rlixxo.
After all, Joshua yielded like an entire pot full with wish cards, whereas Shirozawa granted a mere two points for a stamp card.
The strength of the demonic being should play a role.
The snake mountain and Joshua (plus Lilith, of course) are most likely under far more powerful and complex seals that aren't easy enough to break, than the harmless tapir fortuneteller.