The brother could have the money, and is probably retired, or just retired. I know a barber and his brother that still cut at 72, they have been saving money to do something just like your guys. The oldest brother is very very slow, and the younger one is an ..... jerk.
In your case, one or both may have Alzheimer. You may be seeing the behavior of Alzheimer more than sex offender. But this is still creepy. Keep pepper spray on you and feel safer.
That cornering is terrifying.
Also, its important to speak up and tell him, 'Stay away from me, Go away from me, Move out of my way, Do NOT touch me' You must let them know you dont want any contact with them.
This wierd guy could also be very nice, and if he was homeless is used to a certain, kind of contact with those he grouped with. Who knows, he mave have had friends that did call him uncle. But he is coming on way toooo strong. Older men can be that way, they were trained that way and some find it almost impossible to change.