If you’re not flaunting ToS, then making sure you have all your legal items taken care of (trademark, copyright, patents), you should be fine.

If you’re building something that a cloud provider might adopt or build their own, well, isn’t that risky regardless of the cloud provider element?

I know some companies avoid one provider or the other out of competitive concerns. That seems easily managed with contractual obligations.

Twitter has enabled some borderline illegal behavior, but the account holder has been the one at risk. I don’t think Twitter systematically allows illegal behavior like parler did.