Regarding the shirt - It reminds me of the souvenir t shirts we would buy when we went to the Adirondacks when I was little - nature preserve type places seem to feature realistic animal prints in my (limited) experience, like that shirt seems to be. It does appear to be early 1980s to me. (I say this because I'm one of six kids and my many brothers had many 1970s and 80s t shirts.)
I don't think this person is in the databases. Maybe wasn't even reported missing. I say this because of one of my brothers could have become this person, but for the grace of God. He took off hitchiking in about 1979 with a friend. They worked at state parks around the country, in Florida at one point and then getting jobs out west (at Lake Tahoe at one point in fact, weirdly enough) which they just sort of winged it to get to when it was time. Rides, busses, etc. All cash or whatever back then, no records of travel. At one point my brother became despondent and went to Yosemite and had his friend drop him off and leave him there alone.. he was going to walk off a cliff. Instead he fell in love with being a mountain man... he left when I was about 6 and I didn't know if he was alive or dead until I was more than 30. I'm 42 now and still haven't seen or spoken to him but he wrote a little book about his journey and decision and way of living up there in the Sierra Nevadas now, and one of my other siblings found reference to it and his name, as author, on facebook and that's how we found he was alive. (His book literally begins with "Big cliffs are easy to step off".. that's how I know why he went there. Crazy.)
But my whole point is, we never reported him missing because he WASN"T missing.. I mean, we had an address and birthday cards and letters wouldn't be returned to us.. and at one point he wrote back to me once.. but said he was going on a trip aroudn the world with a great girl he'd met and wouldn't be in contact for awhile... and he'd always been a bad one with writing and calling anyway (those days there was no cellphone or internet of course) .. but then we heard nothing for months then years, till before you know it, years after mom died my other sibling found that facebook reference. I do genealogy research and sometimes would look for his name and social security number in the social security death index but never found anything. Still never occurred to me to report him missing though. He was just.. not talkative we figured. He'd gone his own way.
I think the unidentified male in this case is probably like my brother.
Just my opinion and sorry to sidetrack.
Editing to add: If so, social media could be very helpful. Instead of asking if anyone recognizes this "missing person" who was found, playing up the angle of "do you have a relative you haven't spoken to in longer than you realize who matches this description" type of thing, you know?