If Punk made enough money, and he's an independent contractor, nothing's wrong at all with withholding services until he receives sufficient value. All wrestlers have are their name and the limited years their body has in terms of performing in the ring. WWE never stopped paying Austin when he walked out, he was on his ranch for 9 months collecting his downside while getting drunk. Punk doesn't owe any of us an answer either.
Austin has said several times..he didn't make one penny after he walked out.