ownership of all houses and common areas within the subdivision. The protestors weren't on the mccloskeys' yard - they were on a common area that they mccloskeys are trying to assert squatters' rights on.
https://www.stltoday.com/news/local/metro/portland-place-couple-who-confronted-protesters-have-a-long-history-of-not-backing-down/article_281d9989-373e-53c3-abcb-ecd0225dd287.html