That doesn't make sense. No really. I'm not defending cryptopia, but they don't have enough resources as it is to run the exchange, they couldn't possible be keeping bulwark coins to run masternodes on their own servers.
What you are most likely seeing are people buying BWK, withdrawing them, then setting up masternodes. But not the exchange itself.
Agree with your opinion! However, I think Cryptopia exchange should do better. If their current infracstructures are not good enough to meet essential requirements to provide and support their customers to run masternodes on their exchange, they should not provide masternode-related services.
They only should do it after their infracstructures upgraded and be ready to operate smoothly.
Not scam exchange, but something like greedy one, try to provide as much services as possible regardless of pre-requisites to run them.