As above ^ it’s all irrelevant for the first 2 years, as barring exceptional circumstances they could offer you anything you wanted and still kick you out without even mentioning probation.
Only you can decide whether you want to risk that – if you’re currently employed you’ll definitely be out of a job with no guarantee of one on the other side, and you should have more of an idea of if it’s worth that risk from the interview? If you’re not working now then nothing to lose.
It actually wouldn’t bother me – i’d see it as them being open and covering their own arses. If they were desperate for a filler for the summer and had a bit of brain they’d give you a straight offer and pull it off you after 6 months.