What would make anyone think that the UK will be more attractive to chinese companies when it gets out of the EU?
However, with the EU tariffs no longer applicable to UK in 40 days time, its too irresistable to him.
First, no one knows about this as of yet. Second, if no deal is found on EU tariffs, this is not unlikely that the import taxes will actually increase (whereas you seem to imply that they would disappear altogether, which makes no sense.)
As to regulatory matters, I see no reason why the UK would give up on the CE mark or anything related. They may or may not add their own standards over time, but not in the short term. Many countries outside of the EU do the same. A lot of them comply with the CE requirements, and some have additional requirements for their own market.
As if exiting the EU would suddenly make a country with no law and no rules. Seriously?
If anyone wants to work for a chinese company, as long as they don't infringe on any law/copyright/patent/..., so be it.
Using pseudo-political reasons and uninformed predictions as an excuse sounds pathetic though.