CBS has actually come out and stated that aspects of STO are considered canon
Hell, they've even stated the storyline for the upcoming "Age of Discovery" STO content will be considered canon in the same fashion.
Uh, when and where? I don't recall them saying anything like that at all.
CBS official stance on canon is only what is seen on TV/movies. Not games movies or comics.
Cryptic is working with CBS and the DSC team to make sure their story fits in the show's story, but just like the DSC tie in novels and comics, it is not canon.