It's kind of funny, because at the same time Jobs is explaining why DRM sucks and basically can't be standardized, they were also developing the iPhone which would go on to repeat the whole "only we sell things wrapped in this DRM" thing... except without the sideloading option.
The article you linked adds it's own commentary which has aged like milk. Jobs wasn't so much opposed to DRM in general, as much as he just didn't like it on music. This probably has more to do with the fact that Apple was not a music label[0], and thus he was predisposed to look at music solely as a consumer[1]. When it comes to things Apple does publish[2], such as software, they are extremely protective of it.
[0] And legally, cannot, because of numerous trademark lawsuits with Apple Records, the record label of The Beatles
[1] "They don't want to rent their music" https://www.theverge.com/2015/6/8/8744963/steve-jobs-jesus-p...
[2] "Publishing" in this case means funding the creation, marketing, and physical manufacturing of some creative work. This is primarily what a music label does, and is part of the reason why they take so much from artists.