I mean I'm not really shocked, it was pretty well foreshadowed. It was pretty obvious taking 100 people from every world she visits every time she visits wasn't for a benign purpose, they were clearly some kind of sacrifice or being sold as slaves.
Quite honestly, on a scale of 1-10 on what could possibly be happening to them this rates about a 3.
So 100 maidens from each world she visits, figure she probably does one every 3-4 days, so probably about 10,000 a year. That's really not that many, honestly.
I would also like to point out that this tree APPEARS to be growing the youth fruit they ate earlier. I imagine this isn't going to sit well with Allison when she notices. And was obviously part of Mottom's plan from the start.