If the blades can be easily removed from the razor, the blades can be considered prohibited, to include the razor that is already installed.
There are many items on the permitted/prohibited lists that are questionable.
For instance, you can take a fishing pole, but not a pool cue.
You can take a tennis racket, but not a basebell bat.
My favorite, you can take scissors and a small screwdriver to help seperate them into 2 blades, but can't take a 1" razor blade.
It's just the way the rules are. We prohibit what we are told to prohibit.