Now it has rear suspension-and rigid fork.
.... which is basically what you have with anyone who rides a road tandem fitted with either a suspension seatpost or an Allsop Softride beam.
As noted in the write up, this started off as one of Tom's personal tandems that he rode with his wife Theresa, noting Theresa pretty much rode seated 99% of the time. It suffices to say, Tom experimented with a number of different rear suspension systems that didn't compromise the stoker's pedal stoke by replacing the moving saddle with a suspended rear triangle.
We first met Tom and Theresa at the 1998 Southern Tandem Rally in Selma, Alabama and he brought along a different personal tandem that also featured a suspended rear triangle. It was a 26" wheeled tandem with an open frame fabricated out of very large diameter, thin-walled steel tubing and featured and spring and elastomer rear suspension system similar to the Moot's YBB system except that I believe a small pivot was used aft of the rear bottom bracket. It also had a very long telescoping rear stoker compartment that could be lengthened or shortened and also allowed the tandem to be broken in two halves so that they could transport in the back of their small car and had only a set of aerobars for Theresa... again, noting that putting weight on hands was an issue for her.
The tandem up for sale appears to use a different approach for the rear suspension with a lot more travel and also suggests that Tom was experimenting with a non-conventional frame structure... never intended for mass consumption but most likely just to satisfy his own intellectual curiosity about frame design and function.
but I suppose the only way to check a bike like this out is to ride it.
Short of doing instrumented strain gauge testing and finite element analysis, that's probably true and it's for that very reason that Tom often time built one-off frames like this...
And I do not know of Tom Bruni- or his bikes- but my first impression is that even the best can have an off day
I did and I would suggest that the best and brightest don't usually follow convention with many of their designs and, as noted, often times do things for reasons that we don't appreciate or understand. IMHO, Tom would have enjoyed this 'discussion' and welcomed all critiques with a detailed explanation of what he was was trying to accomplish and the current owner may also have some insight into the design goals as I'm sure he also had a lot of questions about the bike before buying it from Tom.