While people working in the industry undoubtedly know far more than most of the rest of us about the process of acquiring stock, etc., nearly all of them are in the business to make profit. That isn't bad, but it can influence one's approach to conservation, etc. There are many instances of 'industry knows best' leading to major environmental problems (think about many whale species, cod stocks). I am not saying this is the situation with sea horses (I don't have the knowledge to say that). I am suggesting that people's opinions should be judged on the facts used to support them, not on the stength of conviction or on 'being in the know'.
I've been researching the possibility of starting a seahorse tank. Every site I have read says the same thing: buy only captive bred sea horses. This is to reduce the demand on the wild population. But also becuase of their better record in aquaria (something which should be taken into account). There is a role for WC seahorse for the experts and breeders but I have trouble seeing them being sold to neebies. As such, I share the concerns about a major Canadian aquarium vendor selling WC seahorse without provide clear disclaimers, etc.
Sites of potential interest would include:
http://www.seahorse.org/
http://www.syngnathid.org/
http://www.saseahorse.com/