I can see that there's a real danger of "shooting the messenger" here, where the builder is quoting to a client's instruction. There was a similarly heated discussion of Charterhouse in this forum not long ago. I haven't seen mention of a consultant for the Gloucester work. I wonder who has created the new scheme. It's unlikely to be just Nicholsons acting alone.
There must have been a lot of good quality pipework in the HNB instrument which could have been re-used elsewhere. I wonder whether the overly enthusiastic "melting down" comment is really true or headline grabbing, a bit like edgy comedian Joe Lycett's recent "shredding" of £10k.