Confusing interaction between kmail html settings

I have configured kmail to display HTML content globally but not to load external images. I also subscribe to several mailing lists which I ‘trust’ in the sense that I’m willing to load images by default.

When I enable the loading of external content for those mailing lists the external content is loaded, however, despite the global setting the message viewer falls back to displaying the raw HTML unless I also enable view html from the contact. Is this expected behavior? Is it a bug? I find it confusing but wanted to discuss before potentially reporting a bug.