I guess you could say the same thing about that puddle of oil under the car as well. Just keep adding oil and it's alright.If you keep grease in the knuckle cavity, what the outside looks like doesn't matter. That picture looks "normal" for a 30 year old cruiser. Just because something is located under the car doesn't mean cleaning it is forbidden.
Who in their right mind charges 2 grand for a knuckle rebuild?you must be new here haha, search knuckle rebuild and get reading, there's a stunning amount of info on tools and parts needed
$2000 in labour at the mechanics or $200-500 wish if you buy parts and necessary tools
its not hard to do yourself, im currently doing it to my 60