The short answer is 100% no. 

I have broke this code down back in 2016 to see how the setting for the FAN ON was interacting with the tables associated with fuel mixture short term fuel trims. It is far too complicated and unnecessary to explain how this works. Anything I post here, it not only educates some individual that really does not care for more than 10 minutes time, it educates competition that has no clue how all the tables and maps work in the ECU of now and recent past ECU’s. We had this same problem with people wanting parameter this and parameter change that built into the HPTuners software.

However, the longer answer is as follows: 

The best reason is that the coding is calibrated to interact with tables and maps based on FAN ON. I can prove at least 2 visual pictures that FAN ON is part of calibration to the ECU on Throttle Valve Adaptations and Mixture Formation Adaptations. See below ISTA+ calibrations of adaptations. This is also the same process in the GS911 for the BMSX/BMSMP ECU. The engineers have created a process that this change in fuel being added or taken away is called Fuel Trim. Really, the oxygen sensors are what drive the fuel trim readings. Changes in O2 sensor voltages cause a direct change in fuel. The short term fuel trim (STFT) refers to immediate changes in fuel occurring several times per second. The long term fuel trims (LTFT) are driven by the short term fuel trims. LTFT refers to changes in STFT but averaged over a longer period of time. A negative fuel trim percentage indicates a taking away of fuel while a positive percentage indicates an adding of fuel. So the ISTA and GS911 are using the FAN ON temp as the ending point of the calibration process. It takes that reading at that moment in time and writes it to the EEPROM for reading of the adaptations values. You change the FAN ON temp, you change the process and procedure that was designed around it.

FAN ON is not only a temperature setting in the ECU, (which happens to be 214F / 101C ) it also interacts with the design and balance of the cooling system as a whole. 

If you move this FAN ON number, all you are doing is creating more cycling in the system also. 

I have had 3 very smart customers that made sure I was not altering the FAN ON temp setting. Somehow they knew this was something that should not be messed with. I assured them that it will remain as per designed by BMW engineers. Oh, and remember, I ask for the ignition switch and key so that I can re-calibrate the ECU for these EXACT issues of making a major Fueling Change to the ECU from Stock released adaptations.