ViaBTC is a joke: "We want on chain scaling" -> Segwit release imminent (on chain scaling) -> "Let's block Segwit". A bit ironic, isn't it?
If their genuine intent is to block SegWit, then I'm happy to go on record as stating that's unreasonable behaviour. We should at least give it a try and see what impact it has. I'm hoping that the actual reason has more to do with coding compatibility, for example, trying to get SegWit and Xthin working in conjunction and it taking a bit of time to figure that out before BU and others can add Segwit to their code.