I have also heard the garden hose = bad theory, garden hoses are made from PVC which often has other impurities in it. Considering garden hoses are intended for watering plants they don't need to be foodsafe, although the dangers may well be exaggerated.
The other danger is stagnant water left in the hose that grows mold/mildew and bacteria in between water changes.
I think if you use a python setup then the best thing is to turn the tap on with the "tank end" over the sink, then let some water run out and this will flush any contaminants out of it. Then turn the faucet off, put your thumb over the tank end of the hose and walk over to the tank and put it in. Then remove the lower sink end of the python so water syphons out.
Having a good amount of tank water go through the hose will flush it of most contaminants anyway.