The CTO was never a software engineer. They were a developer advocate so had some interaction with code, but was more of a "talk to developers using things and make sure the requirements were passed along to the dev team" sort of guy, rather than someone that knew his technical details (beyond say, the thing he was actively working on) inside and out.
Fosco started out pretty reasonable. When Trump was first elected, he did a "talk to a conservative" series, and while there was the expected disagreement, it was a pretty, civil, positive, well-received olive branch overall. However, like a lot of right-leaning folks in the Trump era, he became more extreme as time went on.
I had some reasonably close interactions with Fosco (not going to go into details with how), but it was being kind of clear that he had started to buy into the "Fox News caricature of what someone on the left is like" — to the point of putting words into the very people's mouths he'd so civilly made a point of talking to prior — and surrounding himself with like-minded folks. For all the talk of "diversity" that he had (and indeed, initially fostered!) he became pretty much the sort of caricature, albeit one of the opposite side of the spectrum, that he was deriding.
In that sense, while there's a lot of holier-than-thou and disgust that the whole Gab situation prompts, I feel pity and sadness more than anything else. Fosco was a decent guy at one point, but even decent people can end up in their own echo chambers. It's unfortunate to see the state that he's in now.