Might as well wait for the inevitably shady/illegal things to take place so it can be banned with reason.

Why would Apple do that? First, there's unlikely to be a big market for this (think Parler) so why would Apple involve itself on something that probably won't matter? Second, if there are any problems (eg security) or ToS/policy violations, Apple can't just assume those will happen. it has to be reactive.

There is literally zero upside in taking preemptive action here.

Why would Apple do that...? Their app store guidelines suck but they've never outright banned apps just on the basis of ideology.

Banning it straight away or not allowing them on at all gives them more power, you just have to wait for them to skirt a rule and you can blame them for their own banning.

I presume they've made the same mistake as that other one did, building on centralized infrastructure so they'll probably end up getting banned from AWS too.

If the lack of outright a-priori cancellation of this app is surprising, that may be an opportunity for one to check one's premises underpinning assumptions.

Why is it surprising?