I decided to rewatch Perun's 2 yrs old Youtube video on 6th gen fighters. His speculations on USAF version of NGAD manned fighter:
1. Tailless & perhaps triangle shaped
2. Very large, approaching the size of a traditional bomber
3. Very powerful power generation capabilities
4. At minimal twin-seated, perhaps 3 or even 4 seated.
Could it be that J36 doesn't just have side-by-side twin seats but also a back row of one or two additional seats? I mean if you want to have four seats you'd want to have two seats on the front row. And that seems to be a major potential motivation for having a side-by-side arrangement.
BTW Perun also thought DoD was right to have 2 separate manned 6th gen fighter programs. He suggested that DoD could further improve on it by having a dedicated light carrier for drones.
To be honest relistening to that old episode in light of recent developments kinda improved my perception of Perun. He must have known his stuff if his predictions and suggestions for the US turned out to be pretty much spot on ...for the PLA.
Well, China and the US have the same requirements aka air dominance in the Western Pacific over vast distances.
A few years ago, my ballpark guess was that to support a single naval drone - a light carrier and a full-size carrier would work out about the same cost. Given his defence economics background, he probably came to a similar conclusion.