As an example, I have been drawing portraits for quite a few years now, and whenever I go on a hiatus and come back after a few months, I can notice my skill not being anywhere close to where it was before I stopped using it.
Sure, after 2 or 3 portraits they mostly come back because of the previous experience, but skill rust is a real thing, and if you think your coding skills are the same because you used to code 20 years but haven't coded for some time, you are probably just lying to yourself.
His skills are slowly eroding. Given that he spent 20 yrs building it up it won’t happen overnight. But the trade off is happening in real time.
I wonder how much of this "you are gonna lose your skills!" stuff matters. And if knowing how to properly iterate a for loop with my eyes closed matters all that much anymore.