I don't think the entire robot would be under 90 lbs, but maybe the base portion.
Think about it. They're giving us a different KOP base so it is easier to attach superstructures. What if part of the game is attaching and detaching different structures (maybe by the human player) to do different things?
Then the 90 lbs would actually be plausible if it didn't include your main appendages or whatever.
I think that sign really is a good clue.
But what does the Baptist Church and post office represent??

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