given that China isn't going to bow to any pressure on its internal politics that we are prepared to bring to bear, i see no point whatsoever in bringing them up.
China has made very clear that the price of potentially very lucrative trade deals - which, for those getting sweaty, means highly skilled, highly paid, very taxable UK jobs to both reduce unemployment and pay for nice things - is silence on its internal politics. speak out - and achieve nothing anyway - and you don't get the deal.
Chinas stance, and its economic power and raft of potential other 'partners' to make that stance a reality, means that 'speaking out' over Chinas brutal, dictatorial, horrible policies has nothing whatsoever to do with making life better in China, its about making people here feel better about themselves.
you either deal with China as it wishes, or it goes elsewhere.