The post explains it quite well, I suggest reading it. I know it is a long read, but there is zero fluff or wasted space on much personal musings in there, all

The post explains it quite well, I suggest reading it. I know it is a long read, but there is zero fluff or wasted space on much personal musings in there, all pure factual content. Tl;dr: very messy legal proceedings and multiple settlement offers (including a proposed gag order that ZeniMax's legal team was trying to force upon Gordon) are the reason for why. And those legal negotiations started less than 2 years ago, after the release of the game. And throughout that whole post, it is evident that Gordon (despite being wronged multiple times in a row) pretty much kept giving them second, third, fourth, etc. chances to resolve it amicably, as he believed it was in the best interests of the projects ultimately succeeding. Only to get taken advantage of and being stabbed in the back multiple times by the same person he decided to give those extra chances and forgiveness to.