Yes, very odd, and I agree there are probably some details not shared that probably could shed some light on the situation.
All that said, I'll just add this: "Tit for tat."
Most of us here have become well aware in recent weeks of many cases where non-US citizens have been treated quite harshly upon arrival in the Land of the Free. German teens backpacking their way around the world jailed in Hawaii. British young lady detained in Seattle for weeks in an ICE facility because she admitted to doing household chores for hosts. My own family members grilled for hours upon arrival for a family visit. There are a hundred other stories we have all seen/heard. Some worse than others. Some very concerning (to some of us), countless others that were well below the Media Outrage Threshold. And some whose experiences have been accepted as perfectly OK and routine by some here.
No judgements from me here today. I'm just saying this:
To most (IMHO, anyone who is being honest), it's quite evident that "there's a new sheriff in town" and America's immigration policies are now being enforced, lets just say, differently, than they have traditionally been experienced.
This is not lost on foreign governments. Perhaps they too have decided to "send a message" by matching - and maybe escalating - the experience for Americans arriving in their countries. Policies coming from the US government, whether trade practices or immigration enforcement, may eventually be met with similar policies as a not-so-subtle way of saying "OK, you want to go there? Well, two can play that game, lets see how you like it." There are plenty of people traveling who could fall into gray areas or edge cases. Maybe this young woman was one of those that previously would never had had any issues (YouTuber? Instragram influencer? travel blogger?) - heck, does every Rick Steves employee have a business visa every time they go to Europe? Don't know (don't care, either) but it's something I bet everyone will now be (or probably should be) increasingly diligent about nailing down.
I'm not saying this is good or bad, right or wrong, effective or a useless waste of time. But nations often do respond to policies they do not like with responses that are reciprocal. In this case, the OP's family friend may have been collateral damage - just someone that they wanted to make an example of to get their point across. Or maybe not. But human nature and the behavior of nations being what they are, I would not be shocked, SHOCKED! to discover there was gambling going on in the casino.
Valerie, I hope things go well for your friend. I completely understand how traumatic this can be (I have my own set of kids that are still freaked out from their experience). Good luck and take care. And to everyone who has ever posted to Youtube or has a blog about your trips to Europe...pay attention to the world around you. Good luck.