they volunteered for military service in a cause they _knew_ was directly contrary to HMG's policy. They _knew_ that HMG was active on the other side. Indeed, this knowledge was (allegedly) a major motivation for them to join up. Take the consequences of their actions.
And, oh... during the Second Word War, there were a few dozen Britons and white Commonwealth citizens in the Britisches Freikorps of the Waffen SS. (Indians, despite being more Aryan than Teutons, were in Frei Hind; there weren't many of them, either.) If they'd faced Empire and Commonwealth forces, it's unlikely that they'd have been taken prisoner. Mostly they were operating against the Soviets. After the war there was a lot of noise about the less than 60 total BFK SS-men. France, the Netherlands, Denmark, and Norway all provided substantially more troops for the Waffen SS. The last defenders of the Hitler's bunker in Berlin were from Charlemagne, the French SS unit. Some Charlemagne men had engaged Free French troops in France in 1944; several prisoners were brought before LeClerc, who asked them why they were betraying France by wearing German uniforms. They sassed him back by asking him why he was betraying France by wearing American uniform. He had them shot. Further back, there is the example of the Batallón de San Patricio, mostly Irish deserters from the US Army during the Mexican American War. (That didn't end well for them, either.) I'm sure that readers can think up a multitude of other examples.
I expect that the RAF would have bombed the BFK if it had been larger and thereby worth paying attention to. I _know_ that Free French and Free Dutch and Free Norwegians flying RAF aircraft bombed and torpedoed ships run by French, Dutch, and Norwegian seaman under German command. This 'news' item is not new, is not unexpected, is not unusual, and is not news.