In theory, it will work.
But not very well.
First, it will not "turn it down". It is either on or off- there is no in between.
Second, it will only go down to about 150-175 degrees, although I am not sure what being submerged will effect the probe.
Third, the dial will be so sensitive that it is almost impossible to get it dialed in right. A tiny nudge on the dial can make a difference of 15 or 20 degrees.
Fourth (and most importantly) the "swing" (for lack of the proper term) is far too great. If you have the temp set high enough for it to boil, then it will likely never get hot enough to shut off again.
Rather than an oven control, I think you would be better served using a stovetop burner controller. It would be completely manual in operation, but you would have far better control.