Funny, grandparent did not show me any "telltale signs" at all, and I am pretty sensitive to awkward phraseology one finds in non native speakers. Not that being a non native speaker is in any way naughty or evil.
That's because your native tongue is one of the Slavic languages. For list of telltales, see some of the other replies.
His post is actually well composed, thoughtful, highly cogent (unlike yours), and makes excellent points.
A reply of a partisan for the other side of the argument. Otoh, I don't like it when it starts to devolve into ad hominems, either.
It is parent who strikes me as being very partisan.
And that, of course, is what makes an argument.
Vsevo Khoroshevo,
Sysrammer
Update: I reviewed your other posts, and the English is generally good. So, I presume 1) You let someone else use your account, 2) possibly because there was a shift change. Perhaps one of your staff of linguist/programmers is a bit weaker or is less experienced, and needs more training.