Well,
- by any standard whatsoever, she is a better representative and more suitable to be there than Laurent
- we have no idea what Philippe and Astrid are doing, but she has a very good relationship with the latter and at least a cordial one with the former. Is it possible one of them could have suggested she go?
- everything else aside, Delphine may have just been the closest geographically-available relative for the local ceremony. Which isn't so strange.
You don't have to have known someone to want to pay your respects to them, or to try and strengthen your familial ties when that's only recently become possible. I like to believe King Baudouin would have extended some of his famed kindness to his niece.
- for the reason I stated above, I don't think she is a better representative than Laurent would have been, but just an equally unsuitable one;
-I don't think either Philippe or Astrid suggested her presence at the event. In the interviews she's given since she became a Princess she said that Astrid was "kind" to her (which I don't doubt) but I don't think they have a close relationship or see each other often, same thing for Philippe. It's more likely it is a private initiative from Delphine and they were not informed (which seems the norm, also reading her interviews): it's fine, she's free to do what she wants as she doesn't receive a dotation, I just think it's not particularly appropriate;
-If she was the closest-available relative I personally would have asked somebody else, without being related to him, but who actually knew and had a relationship with Baudouin. It is not necessary to have had contact to a person to pay homage to him/her, of course, but in a situation like this, where there are still many people living who knew him, it's better. My personal opinion, of course .
As for Baudouin's kindness: he certainly was a very good-natured and kind man, but also extremely conservative. He was fully aware of his niece's existence and wasn't very pleased about it. He was extremely happy when his brother and sister-in-law got back together for real (this picture from Astrid and Lorenz's engagement says a lot, I think
https://www.pinterest.it/pin/739505...49e9709d72129&sender=654922108219969875&sfo=1).
Not to mention that one of his most trusted advisors was Cardinal Suenens, who, according to one of the versions of the story given by Delphine's mother, was the one who told Albert to cut off contacts with Delphine.
So, I still don't think it's the most appropriate person they could have chosen for this homage, but as I said in an earlier post it probably won't be big deal as it won't be the most significant ceremony to commemorate Baudouin