Does it make any sense to wrap the plastic handle of a pan in aluminium foil to protect it from overheating when placing it to the hot oven?
The foil has two effects: it insulates and reflects.
Thermal insulation does not offer immunity from heat. It reduces the flow of heat. In other words, it delays. In this case, the actual insulation isn't caused by the aluminum foil (which conducts quite well) but by the air layers that it traps.
Reflecting radiation would help if it wasn't happening in an oven. Radiation which is reflected away doesn't turn into heat, but inside the closed environment of an oven the radiation just gets converted to heat somewhere else. It will take a while to get to the handle, so it's another delay.
So, in summary, the foil just buys you a bit of time. From personal experience, I'd estimate it at minutes, certainly less than an hour.
MSalters answer is all correct, but even in an oven the reflective nature of foil may help (as it would under a grill, but the effect is smaller in an oven). To explain, let's assume the plastic is perfectly black: Wherever the heat is coming from must be hotter than the air in the oven and the other items in the oven. This is particularly obvious if the oven heats with a visibly glowing element, but will be true even if the element is behind a metal panel. A black plastic handle could easily reach a higher temperature than the air temperature (the nominal temperature) in this case. The foil will reflect this radiated heat quite efficiently, significantly slowing the rate of temperature rise.
Everything will want to go to equiliberium for temperature in the oven.
Aluminium foil is not a good insulator.
Suggest three courses of action:
COA 3 will be the most difficult due to you solution will most likely be large/clumsy and will cost $$$
Use the KISS (Keep It Simple Stupid) principle to solve your problem.
No. If your saucepan can take the heat of an oven, the handle needs no protection. If it can't take the heat of an oven, there's really nothing you can do to provide any practical protection to the handle.
Not only will there be heat transfer from the surrounding air (and radiant heat from the heating element/burner and all the hot interior surfaces of the oven), but heat will also be conducting into the handle from the body of the pan.
In all likelihood, to achieve what you want by putting the pan in the oven will require it to be there long enough that the handle is going to approach oven temperature no matter what you do. So, you need a pan with a handle that can withstand such temperatures.
There are some materials we commonly describe as plastics, like bakelite, which can take a lot of heat, but still much less than what you'd commonly use in an oven.
Bottom line: if it doesn't say oven safe on the label, it doesn't belong there, no matter what you try to do with it or to it.