I mean, he has to be given a credit. We know that he and Snyder were working on the story before it was announced in July 2013. That said, the fact that the hired Terrio to do a rewrite (just two months before production was set to start, and was eventually delayed for nearly four more) should say alot. And the EW article pegged him to be alongside Snyder crafting the DCEU (something that was attributed to Goyer from the beginning), while not mentioning Goyer, should say even more.
My theory?
As reported, Goyer was set to craft the DCEU alongside Snyder, with Geoff Johns (whom we know is co-writing 'The Batman' with Affleck) as a consultant.
Goyer and Snyder nailed down the story around the time Affleck boarded. And like MOS, Goyer was set to tackle scripting duties alone. But when the initial draft of the script came in around November, it was poop, and had the same issues as MOS; Issues they hoped to fix and avoid going forward.
At this point the studio and Snyder was wary, and Affleck likely objected entirely. It was at that point they brought in Terrio to simply polish what Goyer did. But after a few months of working on that, it was collectively decided to do a complete rewrite of it, and delay the start of production until late-May/early-June.
What Terrio eventually delivered was so good, that they decided to move on without Goyer, and hand his former duties over to Terrio, including writing JLA Part I and helping to craft the connective the connective tissue of the DCEU.
That said, Goyer is still working with the studio as he inked a 3-picture deal for his own projects in late 2013, and was a producer on Constantine until it was cancelled.
But as far as the DCEU, Goyer is out.