A Pi won't draw less than a 100ma but it will vary quite a bit during power up. In any case detection at 50ma is quite high. It also seems to be a combined minimum over all the ports on the Anker, as plugging in something into another port will wake them all, is that right?
My chargers/supplies have a threshold of 200uA (0.2ma) to wake any given port, likewise a short or fault on one port will not impact any other port. I wonder if they actually mean 50uA but got the units mixed up?
I wonder what they have changed internally?
Out of interest, this is a snippet I took ages ago of a PAW unit, the power consumption is not at all smooth at all - there are loads of transients. The peak now will be higher than this shows, but I haven't done a new one as I don't have Rosetta available. My meter will do 50k samples a second, and is calibrated.