I have the Lasermax guide rod laser for my Glock 19 Gen 4 now for 6 months. It is activated by pushing the slide lock in like a button. I just recently removed it and put the stock guide rod back in. The problem was that my left hand thumb rests right on the slide lock when shooting, unintentionally activating the laser. The laser would also get activated while carrying it in my Crossbreed holster, as the leather side of the holster pushed the slide lock in. I am currently carrying the gun without a laser. As a home defense gun, I do have the Streamlight TLR-1 on it when not carrying. I am using the Lasermax guide rod laser now as a range tool, just for fun.
It looks like, Lasermax does not make a guide rod laser for your Glock 23 Gen 4. However, I hope that my experience helps you.