I think it's completely fine that Linus invested in Framework, but I personally think that he plugs the laptop too much. His investement is personal and should not interfere with his work. It is good that he discloses that he invested in Framework, But only when the Framework laptop is the real competitor it should be compared to the reviewed laptop.
Don't get me wrong, I really like the concept of Framework, I'm also a big fan of Fairphone (it also helps that I'm a Dutchie), I think that is a good idea that Linus is investing Framework. If I had the money, I would too.