From what I understand, that same document says there's a single Dutch special force[0] in Ukraine. That suggests to me that this might not be about combat roles, but might be about advising or training or something. If it's accurate at all, which both the UK and Ukraine dispute. Although they probably have to do that.
[0] The title suggests 50 people equals 50 special forces, so I guess that means the single Dutch guy there is a special force on his own.