Gubler's absence from Criminal Minds reboot could mean big trouble for Reid
The absence of Matthew Gray Gubler from the Criminal Minds reboot suggests that Dr. Spencer Reid is in danger because he doesn't have the BAU with him.

Given Matthew Gray Gubler's past at the FBI, his absence from Criminal Minds: Evolution could suggest that Dr. Spencer Reed is in big trouble. As an original cast member, Reed's story was explored extensively during the original run of CBS's Criminal Minds. Between that and the character's actual charisma, he's understandably a much-loved player in the police procedural, which makes Reed's Criminal Minds: Evolved absence disappointing. The Paramount+ reboot has revealed little about the boy genius's whereabouts and why he isn't working with the BAU on their biggest case yet. However, for whatever reason, Reed's separation from his longtime FBI team could mean bad things for the character.
Realistic reasons for Reid's absence from Criminal Minds: Evolution due to scheduling conflicts. Initially, it was thought that this was the actor's decision to skip the revival entirely after starring in and occasionally directing Criminal Minds episodes for 15 years. That being said, Criminal Minds: Evolution showrunner Erica Messer eventually revealed that Gubler was actually interested in participating, but couldn't because of a previously set commitment. The good news is that this leaves the door open for Reid's eventual return despite his current form Given his past, that might be a cause for concern.
Reid Gets In Trouble When He Isn’t With The BAU

Despite being the brightest BAU member, Dr. Spencer Reid is considered vulnerable. Although he has proven time and time again that he possesses an indestructible spirit, he still tends to make questionable choices and be taken advantage of. This is why BAU is so protective of him. Separated from them in Paramount+'s Criminal Minds reboot, there is hardly any connection to any of the team members, leaving him vulnerable to those who want to harm him. That's exactly what happened to Reed the last time he was alone - he ended up in Mexico, was framed for murder, and ended up in jail.
According to Deputy Director Bailey, Reed's current job is classified. That meant it could be as dangerous as the one he had before, but without the solid backing of the BAU, his job at the bureau was less secure. Otherwise, any problems with Reed's mother would force him to take another risk for her too. That's exactly what happened to his ordeal in Mexico, where he could enter without BAU's guidance. More serious trouble than before. It might even pave the way for a re-examination of Reed's abandoned Criminal Minds addiction narrative.
Can Gubler’s Reid Join The BAU On Criminal Minds: Evolution?

Technically, Dr. Spencer Reid is still at BAU; he still has his stuff on his desk, and the team is still looking forward to seeing him again. Matthew Gray Gubler has not been ruled out of the show, which leaves the door open for his possible return. Showrunner Erica Messer revealed that the actor's Criminal Minds: Evolution absence was due to a scheduling conflict, not because he didn't want to return, raising the chances that he'll eventually join the revival. Perhaps Reid's absence could even serve as a narrative springboard for Season 2 of Criminal Minds: Evolution, meaning the FBI's boy genius could play a major role in the show's upcoming story.
Criminal Minds: Evolution releases new episodes every Thursday on Paramount+.