If we take the data at face value it does seem to be the case but there could be more to the situation (as you stated). A very long time ago I might have seen some activity on coinjoin.nl in the list but cannot be sure if it is not working.
One thing I have noticed about the Wabisabi Coordinators List is that whenever I visit it, the source shows that no coinjoins were done using the coinjoin.nl coordinator. Even its history shows 0 coinjoins performed in the last 7 days. It makes me wonder if this coordinator is even working or if it's that unpopular that no one even wants to give it a try. If it was offline for a lengthier period of time, it would surely have been removed from the list.