That bento site that says that bit of info, the page looks dated to me, I don't think they recommend that on the official ramen museum website.

I've visited the ramen museum myself, I think most people do go for the resturants found downstairs.
For kids there is this make your own cup of noodles thing. You buy a empty cup of noodle styrofoam cup, then over at the tables they have markers etc that you can decorate the cups with, then you bring it to the assembly line, where you can see them put the ramen in the cup, you can choose what toppings you want, then they seal it and shrink wrap it, then there's this interesting balloon type thing the entire sealed cup goes inside that you blow up yourself (lol sorry hard to explain). Kids (and adults alike) seem to love it.

Is the place a must visit? No, but if you have spare time in Yokohama, I think its a good place to stop by, and try some ramen in the crowded basement.