You should probably read more carefully. The argument criticizes someone concluding that something is worthwhile based on blanket statements of easy or hard. My point is that easy or hard doesn't matter, as ppl have different opinions about them. My opinion is that
1) learning your language is easy
2) learning physics is hard
Based on that opinion i can only say "some ppl" or "Many" would find physics a waste of time, and I can say for a fact that learning your first language is worthwhile (otherwise you couldnt function in society).