I watched the video. You would get fined in Australia for recording a video while driving!
Anyway, you weren't at all convincing re sarcopenia. Why? Late in the video you admitted it was still possible to build muscle in old age.
That means there won't inevitably be sarcopenia if you stimulate hypertrophy in your muscles.
Along with everyone else I believed that in old age it wasn't possible to retain the size that was achieved in our prime. I now know this is false.
It is possible to grow even larger than before and get stronger, too. Sure, it isn't easy and you have to know what you are doing.
One limitation is accumulated injuries. I haven't been able to do heavy bench presses for over 30 years.
About the legs. I don't do any calf work yet my calves are 18 inches cold this morning.
What is difficult is finding the motivation to make the muscles grow. I mean over a period of time. This is a challenge.