If they switch the 3rd Round to 8 teams instead of 6, then I can see the reasoning for second city. You play 2 matches a day in 2 venues.
But with 6 teams, you only play 2 matches a day.
The thing about helping a bid for an Olympics in 2036, is just ridiculous. Hell cities are not wanting to bid for them now, especially the Winter Games. So you are saying that you are trying to help a bid 14 years out? I have a purchased a house in space as well at this time.
But it doesn't matter the number of matches per day in the same venue, what they want is to engage as many fans and european countries as possible. That's also the reason that each team will residue in one of the cities nearby Arnhem and the inhibitants will serve as a supporters of this team in order to avoid situation of empty venues when the host team isn't playing.
I don't think it is about helping with the bid. 2036 is so far away even in 2022 I believe that this is only excuse and they think that if they want to organize OG then maybe they will be interested in helping with the volleyball WCH. I don't know. For me there is no need for another countries to participate in this. Let's wait how it will end. For now Netherlands and Poland are the only one organizers.