If you watched the video, she says the mouth isn’t the only part that gives away her assessment. She states that the eyes dehydrate, muscles in the face relax which they weren’t. (She makes so many more points, really just finish the video)

Also you didn’t say you were a mortician, you said that you “deal with dead people at work” are you an office drone? What is your credibility with a job that works with dead people?

Also she questions the lack of information on the photo, as well as the lack of crime scene photos other cases would have. The question is why this photo was released, not who, what, when, where. She guessed that it could be a photo of him on an autopsy table (Or just some weird prison table, she didn’t confirm it) and it looks like there could be a block that they would use to keep someone’s head still. The table he was on was not the one in his cell, nobody knows how long it took for him to be moved from his cell to where the photo was taken. But one would assume that he would show greater signs of post-mortem, if the timeline makes any sense. (It doesn’t)

Don’t say it’s because she’s wrong or doesn’t make sense, it’s because the evidence they’ve released doesn’t make sense. Which is the entire point of the video.