So...
If someone is good at both grammar and calculus, are they allowed to be a grammar nazi?
I understand HiTech's point which is not wrong, but the two are not really comparable after a certain extent.
In his field, the knowledge of calculus and writing code is a specialty skill, just as certain skills would be for a mechanic, artist, etc.
The proper use of grammar is afforded to just about everyone these days, especially folks with a college education.
Calculus and computer science are not.
Pointing out the rudeness may be correct but comparing it to voluntary, higher education in mathematics and computer science is a bit of a stretch for me.