Yes yes, as mentioned in another sibling comment, your wallet won't allow you to send anything to an invalid address. In this case, the address was not invalid, so why expect it to get rejected?
Obviously the person you replied to meant invalid in the sense of “not intended to receive funds”
It would have been a competent design decision for a system to require some type of initial registration of intent to receive funds for an address in order for a transaction to post.