Do you mean that the platform creators might consider tokens issued outside the TON blockchain as useless? If so, then even Bitcoin could be called useless here, since, as far as I understand, it can’t actually be used on this platform.
No, ChangeNow is the official partner of Ton Poker. You can go to their website and exchange any token for USDT TON / TON.
They are integrated directly in app, so users can change tokens