"although the Companion Bike Seat attaches to the seat post with a "hinged" turn-buckle, so it will provide a little movement for the suspension"
The seller is an idiot.I'm quoting the seller
"We've had a bike seat on a full suspension bicycle and it worked great. As long as you are riding on flat roads, there isn't any issue at all. The passenger on the bike seat won't get the benefit of the suspension, but the cushion is well-padded and it's still a comfortable ride."
OK cwah buy 2 and fit the other on the front then you will be balanced and can carry 2 passengers - then you can see off all the doubting Thomas'sCome on guys, can't you encourage me a little bit?
That's the only decent bike seat I've managed to find!