The longest valid chain is determined by the miners according to where they point their hashing power. Miners also choose what code they run and therefore what type of blocks they produce. Therefore the miners can fork the network and create the longest valid chain even if the majority of full nodes choose not to follow such a fork. Essentially both the miners and the full nodes have the free choice to run whatever code they want, however it is the miners that determine which side of the fork will have the longest valid chain.

Therefore when Bitcoin forks in order to increase the blocksize which will most likely happen since the majority of miners do support increasing the blocksize. Small blockists can choose to ignore the longest chain causing the network to split. I respect this freedom of choice even though you have continuously denied it, which might be very ironic if you do end up on the smaller chain.