Auto Pause while Running, Training and Navigation is active

You don't pause a training. So don't start a training. 

When a red light or a railroad crossing stops me, it's just very stupid to not pause the training...

Just hit the stop button if you want to stop it. Autopause is not supported during a training. On neither Garmin device. 

It's actually 'very stupid' to pause. Yes, it gives you a faster overall time and, therefore a better pace which is good for your vanity, but your heart rate recovers while you're stopped. So ultimately, you achieve a faster pace at a lower average HR and therefore, any VO2Max calculation is incorrect. Higher, of course, which is why you do it. ;)

I prefer to record my actual training exactly as it was.

I agree that auto pause is probably not necessary in that case, but I don't think it will ruin VO2max. Garmin doesn't calculate VO2max from average HR, but rather by identifying "representative segments" where the ratio of HR and speed stays constant. Then it connects these and compares the results with known VO2max measurements. Pausing probably doesn't change much, since the stop will be discarded by the VO2max analysis, anyway.

Your response is ‘very stupid’. 

You haven’t answered the question in any way, only blathered on about your personal preference. 

I would also like to know why certain activities override the auto pause settings and if there is a workaround.