I'd bet that 'one client' getting the ~200gbps DDoS has a massive monthly bill (likely hundreds/thousands of servers) so they're happy to mitigate short term DDoS.
Most dedicated server providers won't go that far if you have a handful of servers.
I know from personal experience that, Digital Ocean, the largest VPS provider null routes your VPS IP for 3 hours minimium for even the tiniest of DDoS's.
I doubt most of the smaller VPS providers can afford to absorb DDoS's even if they don't have overly restrictive policies like DO.