Good picture ... reminds me of the Warner Brothers and their sister Dot buying a garage at a garage sale.
As for the idea of aggressive possession is part of our common law whereby a squatter can under certain circumstances actually gain possession of a property ... but it takes years to accomplish, in some jurisdictions it takes decades.
And among the various requirements is that the occupancy must be notorious, reasonably known to the owner, actually aggressive (trespassing) meaning simply putting out a “welcome” sign could technically invalidate any attempted claim, and also (though the list here is far from complete) that the owner or their agent not visit the property during the time (doing so resets it).
So, yes, this is a thing ... but, no, the guy had no claim for it ... /captain obvious
The Animaniacs were rather good.