Considering her future job as queen will involve a lot of diplomatic and ceremonial functions it does kind of make sense to me that you’d want her to gain some international experience.

Also on a personal level i’d imagine it is much easier to have some resemblance of a private life in a foreign country, especially at a prestigious institution where plenty of others share notable backgrounds, compared to going to a local university where everyone knows who you are. In a small country like Belgium you probably don’t even have much choices as to which university even offers a good program in your chosen field.

Edit:

Elisabeth initially studied at St John Berchmans College in Marollen, Brussels from September 2004 until August 2018. This marked a significant change in Belgian royal tradition, being the first time that a future Belgian monarch’s education has begun in Dutch

In May 2020, the Belgian Royal Court announced that Elisabeth would undertake military training. On 31 August 2020, Elisabeth entered the Royal Military Academy in Brussels, studying social and military sciences

- wikipedia

Really seems like the worst candidate to make this accuse against

To me this news seems more targeted towards european audiences, which couldn’t vote for Trump anyways. Normally you’d expect someone like her to be the last one affected by something like this, if at all. So this drives home the point that it can literally happen to anyone, not just certain groups.