If two trains are heading toward each other on the same track, one way for momentum to be conserved is if they pass through each other. Even though that's not w

If two trains are heading toward each other on the same track, one way for momentum to be conserved is if they pass through each other. Even though that's not what we observe in the real universe, its existence as a mathematical solution implies that mass is an illusion. How is this argument different from Godel's?