Does everyone have "clogged" arteries but do well with them?

Given the American diet, and his age, it is a pretty good bet that he has arteriosclerosis.

You don’t mention what his cholesterol levels are. That makes a difference.

This past spring, during a routine physical, I mentioned my running had become slower and I had less stamina than a year earlier. even though I had just participated in a 10 mile race in almost the same time as the year before, my shorter runs took 10% longer. I had no other symptoms or indications of heart disease, except for consistently high cholesterol levels in the 230— 245 range.

My doctor ordered a stress test, and I was found to have “small anomalies.” This was followed by an angiogram. During the angiogram, two arteries were found to be significantly blocked, and stents were inserted.

I don’t feel better or different, but my running has improved.

I doubt the blood clot is really related to clogged arteries (though I hope his doctors aren’t dismissing a blood clot, especially in or around his brain), but there is a significant possibility that he has some arterial blockage, as @zenvelo, considering his age and the typical diet. A lack of chest pains doesn’t necessarily indicate that he has none. My father once went into the hospital for chemical exposure, but while he was in there they ran a battery of cardio-vascular tests and discovered that he had three arteries that were 90% (or more) blocked and scheduled a triple-bypass operation. Yet even with the three blocked arteries he had never experienced any chest pain and been extremely active and working every day. He was 43 at the time.

^^^^^ Good heavens; 43 with blocked arteries? Do you have any knowledge of what kind of diet he had? That’s terrible.
My BFF’s sister, 84, is morbidly obese and had triple bypass ten years ago.
She’s living in a very nice assisted living place and , besides some loneliness, is usually in great spirits. Oh-her stitches to close up her sternum popped and they had to go back in to staple them.