No he didn't. Levenson overruled the prior judgement of Justice Wilkie that the activities of the Stoke jihadis could not be considered as equally serious to those of the London jihadis, (whose sentences were not at that time subject of appeal) therefore could no longer be impeached. He then commuted the sentences to fixed terms. He made no other abrogation to any other sentences save minor cosmetic adjustments to Mohibur Raham's. It's a straightforward smoke and mirrors revision of those on IPP terms, in response to the ECHR ruling the previous year. The fact the court could have upheld the IPP is a completely irrelevant, the ECHR would have ruled against it immediately on appeal.