If a company extended you a full-time job offer knowing that they were only going to use you for 2 months and then get rid of you, you'd be pissed, and so would HN when you told them about it. People would be disinclined to accept job offers from that company, once they found out what happened.
Legal commitment isn't the only kind of commitment.
Understandable, but I've seen several people let go because they didn't mesh with a company culture, within a probational period, and I think if it were me I wouldn't hold any hard feelings if such a thing were to happen.
Legal commitment isn't the only kind of commitment.