It appears to me that you think(?) that the DFDR starts operating when an airborne condition is sensed by the L oleo switch (and relay R2-212).
Nah, I always had it clear the DFR was working way before the airplane was in "air mode". I had guessed upon release of parking brakes. Incidentally, the DFR seems to have data from many, many flights before this one, so maybe other diagnosis are possible (i.e. did the switch to "fly mode" recorded by it ever failed, etc).
It's just that we don't know for sure what the CIAIAC means by "a sensor in the front wheels changed state to air mode". We can only guess they mean what we think they mean, as discussed before (i.e. R2-212-D).
But good reasoning.
I also agree that a "possitive, reverse logic" TOWS is in call in new airplane designs.
You push the handles and a voice comes up: "TAKE OFF CONFIG OK".
If you don't hear anything: TOWS are not operative, so you are NOGO.
If you hear: "BEEP - SLATS - BEEP - FLAPS" ... you know what you should do.
I also agree that, technically, MEL was probably not well applied in this case.
Although most engineers would've done the same thing, MEL probably only stated that the airplane can fly with inop RAT probe heater in good weather. It didn't say that a WORKING HEATER could just be disconnected. Also, at somepoint, somewhere, I read that the technician (from memory, but I noticed the caveat) "isolated the problem to the RAT probe heater .... more specifically to the circuit that controlled when it was on ..." So, perhaps, the technician DID know that the R2-5 or related circuitry was the one producing the problem ... and I don't know why he could've fail to see that it would also affect other non-MEL items.
Of course, if the problem is isolated to ONLY the heater being permanently on for "no reason", then it can be disconected and be done with it.
But that requires better diagnosis.
It's not a RAT probe's heater failure. The RAT probe heater was working just fine (pbbly). It's something else's failure (i.e. R2-5 relay), that is making the heater do something "ahead of time" (i.e. on the ground instead of in the air-only).