To me it looks like the notch in shaft #216, would ride over gear # 210, which rides on shaft # 213, which looks to have a detent.
If gear #210 is slid so it doesn't engage gear # 207, the cutterhead and feed rollers would be disengaged. Maybe to be able to turn them by hand to change knives.
I agree that having to pull the small knob# 219, would be cumbersome, if stopping feed is needed. Which is something you want to be able to do fast. My Boice-Crane planer has a big D handle for that.
The table roller pins #231 just spin and don't want to come out. The set screws #230 are out. The end of the roller pins are slotted to adjust with a screw driver. (They are eccentric to raise rollers)
In the center of the slot, is a threaded 10-32 +/- hole. I can screw a machine screw in about 1/2" and it stops.
Thinking of using a slide hammer on the screw. The roller pin # 231, just goes into the bearing inside the table roller.
Darn aggravating. Don't want to muck it up.