>We can read Egyptian hieroglyphics.

Only because we found like one stone hundreds of years ago, if that was not the case we probably could not have done it.

>Anything written in simple English will be understandable even by an alien species in 100,000 years.

[Citation needed] This seems like quite an assumption.

Anyhow, the situation he sketched was that some random guy develops a fields with cylinders 300 years from now, how reasonable is it that he somehow understand the language or goes through the effort to translate it? I would wager pretty slim, I can barely understand text in my own language from 100 years ago.