Well, first of all, Ray is kinda old fashioned in alot of what he believes but that is one of the more untrue statements he's made. If you open a scope by removing the ocular or objective end you will have moisture when you attempt to reseal it. Scopes, at least the good ones anyway, are purged several times to remove any moisture that might be present in the environment they are being sealed in to begin with.
To answer the other question about leaking, well that is mostly true and depending on how well the scope is sealed to begin with will mostly determine how long that process takes.
