Yes! Targeted DoS is one way to force traffic to your evil exit node, and also to attack onion service anonymity (by forcing the service to choose a new guard).

Yes! Targeted DoS is one way to force traffic to your evil exit node, and also to attack onion service anonymity (by forcing the service to choose a new guard). The 10/90 attack you're describing is probably not feasible due to monitoring by the network team. Those remaining unaffected nodes would be easy to spot as malicious relays and get removed from the netwotk.