Boris will likely abstain. I doubt he will feature much in politics unless or until Labour win the next general election. If that happens, as seems likely, expect him re-emerge shortly thereafter.
My Thai wife and I were married in Taiwan 1990 after which we had our marriage licence certified by the Thai embassy in Hong Kong. This has been accepted by Immigration in Bangkok when applying for a visa based on marriage, and for subsequent extensions.
It's entirely for the Thais to decide how they deal with fellow Thais, and entirely up to them how they choose to deal with foreigners. If they wish to be tougher on visitors than their own people, so be it.
This poor man apparently had many troubling issues and had previously contemplated suicide. The Thai partner should, however, be thoroughly interrogated. Problem is, that will likely never happen.
Just a continuation of the way in which Thai people have always been governed ie kept in the dark and fed on excrement. The only problem for the ruling classes, and why their days may be numbered, is that so much information is now available on the internet.