I've just watched a documentary that was shot and released a few months/1 year? before the reunion. They explain that Axl refused to speak to Slash for years because he thought that the real Slash had died in the lobby elevator where he was declared dead for 8 minutes then brought back to life, his soul had flown away like a crow and a new soul now inhabited his body, so the Slash we see is not the GnR Slash that we used to know but a brand-new person that Axl is afraid of.