Michael Eavis said he misses the lack of politics, Corbyn is also very strongly opposed to the Eavis family on animal welfare issues but they still invited him on stage. I still think he could but that's more about Morrissey realising it's a festival for people wanting fun and not animal torture videos.
If you mean some of his other views then i don't know what has been said by the family, so maybe bridges have been burnt and it's never happening but i haven't read anything that confirms it.