Monty's dark ride proves that he had his claws prior to joining the band
I’ve seen a lot of people recently saying that Monty couldn’t have killed Bonnie due to him not having his claws before he joined the band, at which point Bonnie was already dead. However, I believe that his own backstory ride disproves this.
In the two photos I’ve attached, you can see that while Monty was doing his one man band attraction, he was already playing bass. He is holding a bass in both the pictures. Since none of the messages we find in Security Breach are dated, there's nothing to say the one about Monty's new claws couldn't have been given to him when he first started playing bass for the one man band, aside from a message talking about 'adjustments' having to be made when he joined the band. This however can be explained away as adjustments needed to give him the Glamrock style, such as his mohawk and new paintjob. In addition, he is actually pictured with his black claws on the top image, through not the second image however I think this is just because the tips of his fingers and as such his claws are on the other side of the bass.
So yeah I'm about as sure as I can be that Monty had his claws prior to joining the band, and I feel this is just one of many things that points to him being Bonnie's killer. I don't have anything against the guy, I'm actually a big Monty fan, but unfortunately our boy is guilty. The real question is whether he did it of his own accord, or was manipulated/controlled by The Mimic or even Vanny. Not sure about that one for now, but my gut feeling is the latter.