From behind your computer it's impossible to say anything that makes sense, especially comments like:'
it must be right on minimum at that time!
You know the RVR reading from the tower when they started the approach? I don't think so.
BTW
The DA in SJJ is 2243' for cat C acft (Missed appch climb gradient mim 5,0%), which is 600' AGL (ceiling is not required for this approach anyway).