[Well, since the UK is still part of INSTEX, this decision shouldn’t come as a surprise.]
INSTEX is a nothingburger. Any European company that provides goods or services related to an INSTEX transfer to/from sanctioned countries is frozen out of the US market. Executives in European companies that remain in the US market and do these prohibited transactions are subject to arrest everywhere the FBI has any kind of writ. Doesn’t matter how many removes and shell companies they set up as intermediate cut-outs. Very few European companies are gonna subject their executives to this kind of legal jeopardy until the US is a much smaller market for them than it currently is. The arrest of Huawei’s Meng Wanzhou isn’t just a warning shot targeted at Chinese execs. If Uncle Sam is willing to take on the junkyard dog that is the Chinese state, whose creature Meng is, European execs are basically mulch before the wood chipper of American hard power.