The quarantine docs you linked make it look like this is configured per-customer, so if the author's email did in fact get quarantined, its because IT configured it that way not because of a Gmail bug.

Also:

> For a quarantined inbound message, the intended recipient receives no indication of the message unless you release it for delivery.

So the recruiter wouldn't even see the email in their spam box. It just wouldn't exist as far as they can tell if it was quarantined.