I still like my theory. Just because it's wrong is besides the point. To my flawed knowledge, knight crusaders looked nothing like that. But it appears that now they do. The benefits of getting old.
Although admittedly, there was only one gatling arrangement on the megabolter and it wasn't stooped enough for a normal reaver.
I'd still rather a baby reaver than a single knight, but they'd be about the same in narrative terms of writing them into the backstory of the game.
The orbital laser being a cooldown for it pointed to something better than a random knight, so perhaps he's a seneschal story-wise. Not that knights aren't powerful individuals, but it's odd that they'd be calling down laser bombardments instead of the space marines themselves (or a titan). Could be wrong about that being the cool down bar as well. I have been known to be wrong before
edit: incidentally, the 25yrs of lore stuff was more-so to say "I know what a knight is and the lore behind them", not "I know all". The wonders of the internet and its beautiful lack of tone conveyance. Apparently I didn't know what a knight looks like these days. Nor did I do one bit of background research into the topic/game. Hazy memories from your childhood are the best kind. Also, the best way of being wrong is when someone thinks you give a fuck, and they do. It saves a lot of research, and tends to lead to more correct knowledge.