This is very unethical behaviour by a host.
Hosts are penalised and that person was, because you were offered a rebook link, so that tells me the process correctly kicked in. Those dates will be blocked off for that host and they will get a penalty on their host rating. Say goodbye to Superhost if they had it. I have had to cancel a reservation unfortunately (even 1 hr after the guest booked when i realised my calendar sync failed) and I was penalised with a fee as well that went towards the guest I believe.
The problem is I think some unscruplous hosts go and setup another profile for the same property. I suspect you will find its a different host profile. It's the only explanation.
My solution? Only ever book with hosts that are either super host or at least > 4.75 IMHO. They will be ethical. The other thing is, whils t that host was unethical and it was their fault, hosts do survive by charging top dollar in peak times. I have been caught out taking a Xmas booking at low season rate accidently but I had to suck it up. Hosting isn't a very profitable business tbh, many of us do it for spare change and the love and a small secondary income, not for huge profit. Just something to consider...but not excusing that host. Maybe looking for a deal at peak period isn't going to get the outcome you want....
Regs
MK