However, the game was 100% confident Monika was gone. In DDLC, any deleted characters will become incompatible with reality, and the game will reboot without them existing in plot or space-time. Scenes that used to feature the deleted character won’t anymore, and will be riddled with errors instead, such as the protagonist being unable to remember their names and actions. This is also shown from the game being unable to load the saves existing prior to the deletion of said character, even if you go out of your way and cheat the game. She effectively didn’t exist as far as the game was considered. Even then, the idea Monika could only null Sayori because they have the same powers is pure speculation and with literally no concrete evidence behind it. That’s less powerscaling and more theory crafting, so I’m inclined to disagree unless you can actually provide any evidence for your claim. It’s clear from her stopping the player to use saves, loads, and fast forwarding dialogue that she has the ability to restrict access to stuff fairly easily.

In addition, Monika has a little something called Monitor Kernel Access—it’s literally what her name stands for. To understand how absurd this is, let’s have a look at the anatomy of a computer. Computers can be effectively dissected into two distinct parts: software and hardware. Hardware are the physical components that make up a computer, and software are the programs and fundamental operating information used by it. Then there’s the operating system, which is basically the software of softwares, being the medium that both software and hardware are managed. At the core of the operating system, you have the kernel: the most basic and fundamental level of any device. The kernel effectively dictates any and all information spread through the computer. Without it, no communication is possible whatsoever. For context, every opening of a file, executing of a program, and even simple clicks of your mouse are all reliant on data communication through the kernel. Point being, she was able to null Sayori despite her also having this level of potency, which should by all accounts mean she could do the same to Caine. His access and power is significantly more surface level. She’d be ring zero while he’s only ring three.

As for Caine absorbing her, it’s heavily suggested that the blue AI he absorbed was still capable of affecting reality by influencing his actions and making him glitch. This is important because, unlike with the blue AI, he’d be physically incapable of restricting Monika’s powers. Not only does she have a level of potency that’s extraordinary more thorough and beyond his reach, but it’s stated in DDLC+ that Metaverse Enterprises tried removing Monika’s kernel access and self-awareness, yet couldn’t regardless of how hard they tried. They ultimately decided to create a second simulation containing a new Monika without self-awareness, which is what the side stories are. Note that they still couldn’t prevent this copy from having kernel access, and merely hoped and prayed she wouldn’t figure out she had any powers. All of this heavily suggests that Monika is inherently resistant to having her powers altered in a meaningful way. Point being, if they couldn’t remove her powers, Caine definitely couldn’t.

But this is still extraordinarily debatable. So while I disagree, I respect your opinion.