If so, will there be people 'looking after' him? Easing him through controls, jumping food queues, etc?
I think 750 miles in 3 days, which is a fairly normal PBP schedule for a strong-ish unsupported rider, would be a decent return for the time spent. The real problem is the time lost before the start, but I imagine a bit of diplomacy could help sort that out (helpers to log the bike through and 'sign in', while Steve is off riding bike No.2 to Mortagne and back, that sort of thing). Likewise, if Steve's attempt is demonstrably going to plan, I would have thought qualification might be waived too (it's been done before).
And it's perfectly possible to ride a 'lonely' PBP with very little or no queues at all. One year when Sheila and I rode together, at one control (I think it was Loudeac of all unlikely places) we literally were the only two riders in the entire control. We did this by setting off with the fast group, and dropping off the back - the next group behind us were the 90h starters and that year we had a 6-hour start on them.