JayJay My experience is that from signup to being able to post or activate account should be 24-48 hours.
That might help filter out some miscreants, but it would be pretty troublesome for people whose devices are in a boot loop or people who are stuck during an installation.
JayJay And if also implemented the way that once you do your first post, receive an email with a link to verify/activate first post then it should be very effective.
I think this fake-airline-phone-number spammer would have waited 24 or 48 hours and clicked that link.