On wikipedia, they even call Jammu and Himachalis "Punjabi" when they are anything but. Neither Seraiki, nor proper Potoharis(i'e ones who aren't recent migrants) are Punjabi. Beware of those "greater Punjab" nationalists with an agenda of reviving Ranjit Singh's empire(lol). Seraikis and Potoharis are distinct peoples, with little to no ethnic affinity with central Punjab. Even intermarriages are rather rare.
I think he was talking ill of Sindhis as well. As for gas, Sindhi fields are rather recent. Before it was sui gas which the entire country used and depleted. As for proper pashtuns, well it's true they don't make anything, but Tarbela dam is surrounded by hindko speaking Pashtuns mostly.