KLM outsourced the operation of the lounge to French food group, Sodexo, a few years ago.

I would not at all be surprised if the fact that one of the lounges is still open is due to Sodexo's insistence on their contract being honoured, rather than this being a "decision in KLM" being made by "Dutch people"....it's quite easy to imagine a contract being concluded between the parties that had absolutely no provision for a week- or months-long shutdown as KLM may have done had it been totally in their hands still, as I doubt KLM ever envisaged a scenario in which they would wish Sodexo to shut up for an extended period.

As such, this may be more a "French decision" than a "Dutch decision"...

(Sodexo caters in a lot (if not all?) Dutch prisons, but many of their catering contracts are likely to be inoperative right now, so I would expect Sodexo to push for any cash that it can. If Sodexo insists on still being paid by KLM, then KLM may as well insist that they actually run the lounge for the duration!)