The title shows a surprising question I noticed on Quora, so I have decided to give my answer in a separate post.
I replied there but then decided to elaborate a bit more in this text. I was indeed perplexed with the question, but even more with some of the answers. The “best” is shown in the screenshot below:

The person is a “most viewed writer” in various categories there, and with some expertise related to health, forgot details. I tried to tell him that this was not exactly so. Then he re-shaped a bit his reply but remained firm in his position.
Now, I myself am a 63 years old untrained person, I never do any exercises, spend days at computer, the usual stuff. But I was reading that comment just a few days after coming back from the Dolomites in the Italian Alps. I climbed to the summits of four mountains over 3000 meters high and this within one week. Those climbs are described in my Italian page in my mountaineering site.
I also tried to tell him that once I was visited by my 70 years old friend, a university professor who never climbed in his life. He was spending days teaching and without physical activities of any kind. So we drove 1000 km to the Alps and we were (again) 4 times above 3000 meters, two times on summits and two times to high points in the mountains. In fact, I have him in some pictures in the mentioned site.
This is not all, I have seen much more in the mountains in my 40 years of mountaineering. See the picture below, this elderly man was descending from Fluela Schwarzhorn (3146 m) with his grandchild in the kid-carrier pack. I can tell you, he was not “chocking” as you would expect from the comment above. In fact, we had a pleasant conversation, and I asked for permission to take this photo and to add to my site.

Should 50-plusers climb mountains?
I would say the following: listen to your body, and ask your doctor.
If you are seriously overweight then do it slowly. Remember that your muscles carry too much weight for your heart. I have an experience of this type, although I have never been seriously overweight. But after running regularly for many years, I had to stop because of knees issues.
So in the course of years, I was gaining weight. When I was at 82 kg, I said this must stop. My wife played a great role in this, I gave her free hands regarding diet. So I lost around 17 kg till I reached 65 kg. This was my perfect weight, the same as it was when we met many years ago.
After that, I climbed Teide (3718 m) on Tenerife for my 7th time and was surprised how easily and quickly I could do this. Then I repeated it a few days later and it was the same. I climbed it in around 3 hours and 15 minutes as compared to more than 5 hours in the previous climbs. The explanation is simple, imagine that I was carrying a pack with 17 kg of weight. This was my lost weight due to the diet. I surely could not manage to do this so easily.
To stress that I was well over 50 at that time. So now back to the issue. According to a research paper, “physical exercise is considered an effective means to stimulate bone osteogenesis in osteoporotic patients.” Also, according to yet another paper, decline of muscle strength is an aging process that develops after the 30th life year.
As you see, bones and muscles naturally become weaker, so physical activities help to slow down the process or even to reverse it.

One more example. I climbed Mt Fuji (3776 m) in Japan (the picture above is from that climb) and this was an overnight tour. In the morning I could see a long line of elderly people walking up. They would go a couple of steps and then stop, then again the same and in the same tempo. This was a pilgrimage for them. This mountain has a special meaning for Japanese.
So elderly people do climb mountains, they can do this, and there are no reasons why this would not be so.
You might want to read my text with various questions and answers about hiking in the Dolomites mountains in Italy. If you want to know how to monetize all this check my text on how people make a living hiking. See also my text about differences between hiking and mountaineering.
Thank you for reading. There is a comment box below so let me know what you think.