I would hope not. AFAICT Zello is breaking no laws in their home country, and is not breaking Amazon's TOS. Although it wouldn't be the first time I've been disappointed to see a US company bend their rules to accommodate unrealistic requests from dictatorships.
TOS can be amended. This seems more like the sort of thing you hire CloudFlare to handle, not AWS. Why does this service need to operate from "dozens of subnets"/"14 million IP addresses"?
I’m not sure the service has that many addresses, just that’s as far as Russia could narrow it down to block it. Otherwise they could just switch IPs and keep rolling.