The description provided in WKK simply doesn't match the scene as it plays out in TMOE. Absolutely none of this occurs in the episode:
- At this point the governor moved to stop the disagreement becoming more heated. Noting my presence in the chamber, he suggested they continue their discussion later.
Not one bit of that occurs. The governor doesn't move to stop the disagreement becoming more heated. The presence of the mystery man you're calling Stevens isn't noted. And no one, least of all the governor, suggests that the discussion between the Doctor and Kettering be continued later.
And our rule on novelisation (and by logical extension, novels that contain elements of novelisation) is is that, in the case of discrepancies, the scene as recorded is the one we go with.
Beyond that, the guy you're talking about is Arthur Linwood. TMOE is pretty clear on that point, naming the body of the guy you've taken all these screenshots of.
WKK, as far as I can tell, appropriates the televised Linwood and tries to insist that whom we're seeing on screen is Stevens, or at least that both Stevens and Lindwood were on screen. But it doesn't appear so. Instead, what happens is that Linwood is the one lurking around the machine, and the one who's found dead on the floor later, and the one on whom an autopsy is carried out.
Sorry, but there really isn't anyone who could plausibly be Stevens that's actually on screen.
It's really important to remember that TMOE was first released to home video in 1998, whereas WKK was released in 1996. So David Bishop likely was working off his memory of the episode — or, more likely, the novelisation — not the kind of careful study that we can do today.