I agree. I'd love to see more details on what the guy felt he was entitled to. I suspect there was a contract signed early on in their dealings that the author of this blog post is not being forthcoming with.
I also think there's more to this.
In the event of no contract, winning this is basically one court visit, plus a cost order against the broker.
In the event of a contract that specifies no payment until the deal is closed with the broker's buyer, that's also going to be one court visit with a cost order against the broker.
The only reason to pay him is if the contract said "in the event of a sale" with no further qualifiers. I'm pretty certain it said something along those lines.