I teach tons of players every day, and no, if it looks like it will hinder playing/lead to injuries, sure- stop doing it. But what this guy is talking about is totally fine. I suppose you jump all over people for using a pick too?Sorry, but I think is bad advice, especially for a beginner. A technique that sounds good and feels comfortable now might turn out to be bad for you in the long run either by hindering your ability to advance beyond a certain level (which I think is likely the case here) or by causing injury over time (probably not the case here). Now is the time for OP to get his technique in order so he doesn't develop bad habits that will be hard to unlearn later on.
To be clear, I'm not saying that there is only one proper or "good" technique, but there are definitely bad ones.
Again, if it sounds good (meaning the technique makes you sound great) and FEELS GOOD (meaning doesn't hurt), do it!