He's not wrong, but he's missing something.
See, he's talking about playing at a store aimed at us and bringing in people who play Pathfinder, 4e, and other things.
That's great! Bring them in! But there is more.
I have mentioned how my son started a new game with total newbies. Well, their tenth game is next week and there are now 5 regular players and they are recruiting more, all of them fresh to RPGs. That, to me, is even more critical than exposing people who play other games to the OSR - bringing totally fresh blood to RPGs in general.
And it doesn't just have to be teens.
Think about how long you have been playing RPGs. Now, in that time how many of your non-gaming friends and co-workers have you tried to 'bring in'? I have asked co-workers, classmates, and relatives. My most daring was either the guy sitting next to me on a 6 hour greyhound bus trip or a girl I met on a blind date on our second date.
She and I have been married for almost 25 years, now, BTW.I have had a lot of success bringing people into RPGs just by asking 'want to come over for game night?' and not saying anything else. I make sure I have a wide range of games - HERO system, Star Wars, Marvel Super-Heroes, Traveller, and (of course) AD&D. We talk to them about the movies and books they like and then pull out the game that seems most apropos. That date? HUGE Star Wars fan, so it was WEG's D6 Star Wars. These days it is easy to start with the LotR or Hobbit movie franchises or Marvel, but it all works.
Another thing Ii do these days is have stuff ready to email them - PDFs of OSRIC, character sheets, party log, and a simple free adventure module. As a family we buy those Pound O' Dice packs as needed so we can hand them a set of dice, too.
Yes! Play in public! But also talk to the people you know.