https://www.sealantsandtoolsdirect....7JNnlcqTLHNuDQI0HQgnY7Hl6hGO7v0BoC2bMQAvD_BwE
This production version features some of the bits I mentioned such as a box extending to the rear to prevent an exposed blade when you push past the blade.
It also has a guard to prevent you placing your hands where the blade passes, although I'd prefer a guard that went all the way across if you don't have a suspended guard instead.
also has a mitre stop to prevent you pushing the sled too far.
I guess Rockler are happy to produce and sell it as a viable product. Although that doesn't necessarily mean it is safe as I've seen companies selling chainsaw blade edged carving wheels for angle grinders.