Politicians are opportunists, and sway anyway they think will build support. That's "democracy!" I've spent time with a Labour Councillor both at work and as a school governor, and he said that he would have become a Conservative councillor if that meant certain election. He was shortlisted (last three) as a Labour candidate for a secure Labour constituency, and only failed because he lived outside the constituency in question. He is an accomplished wordsmith, but lacks substance.
Corbyn is different to most. His beliefs are strong and unshakeable, and that will create relentless difficulties. I quite like his naive take on everything. I don't believe that he will survive long as leader.