One of the things it mentions is the bike crash, there was an investigation but they couldn't find proof for it being anything other than an accident.
This is one of those things that are unknowable by the general public. It may have genuinely been an accident, but it may also have been an assassination. In both cases it is possible, even likely and expected, that the official account be the same.
A little potential snag in the story, though: "Nothing points to foul play, the Volkskrant said after speaking with people at the crash scene. Though, an anonymous MIVD employee told the newspaper that Van Sabben “paid a high price”" [1]. Perhaps that's there in the original piece you linked to: "‘Hij heeft een hoge prijs betaald’, klonk het bij de MIVD."
[1] https://nltimes.nl/2024/01/08/dutch-man-sabotaged-iranian-nu...