If at all they do not want anyone to mail them through
support@coinbase.com, why still leave it active as their contact means on various articles and contact details written by them? They should remove it ASAP and stop feeding people with the wrong information.
This is very unusual because there are certain procedures for managing an email domain. Usually, all "other" unofficial addresses are directed to one of the active ones. Most often, if the user makes a typo, someone from support can still catch all the requests.
However, something like this would not be the first illogicality regarding Coinbase. Certainly, this matter does not confirm the OP's claim that Coinbase should not be trusted, at least not for the reason stated.