I'm here now that I've seen the news
On the one hand I'm surprised he chose right now, but on the other hand the writing has been on the wall for about a year now. It has been pretty obvious for a while that Taylor is just going out and swinging the bat and having a bit of fun. All of his high scores have come from T20 style slogging rather than the grittier sort of knocks of the early 2010s.
I think the 2019 WCQ campaign sucked the soul out of the senior players. The Heath Streak stuff couldn't have helped. They've still put in decent performances for the most part, but the heart isn't there any more. They aren't in this years T20 WC despite the Taliban probably getting their team in, they don't look all that likely to qualify for the next ODI WC... for BT/Williams I think it's pretty understandable that they are fed up with it all. They've got nothing left to prove. Both will go down as Zim legends. Ervine/Raza came on the scene a few years later I guess, but it still applies to them.
This is a sad day for Zim cricket because I think we all expected that when BT left last time it was only temporary, but this time we know it's permanent.
It's the end of an era, BT is the last link to 2004 and he's transcended quite a few eras of Zim cricket. It won't be the same knowing that he's not there to save the day.