This is classic example of revisionism going on as I said earlier. Shalwar Kameez was not Punjabi but from Frontier region of Pakistan. If you go back to 1940s all Pakhtuns wore Shalwar Kameez. Whereas many Punpabis [Muslim and Sikh] wore a Kameez with wraparound. So to claim Shalwar Kameez as Punjabi is utter rubbish. The fact is Shalwar Kameez was more centred around the Af-Pak borderlands. After 1950s rest of Pakistan followed suit the Frontier and adopted the Shalwar. Now we have Indians twisting history because they have discovered the Shalwar Kameez in particular post 1990s.
Even your Sikhs did not wear Shalwar Kameez until recently. If you look at 1947 footage during partition you can see Punjabis on both sides wearing this. Then the Sikhs worse a tight Pajama/kurta. And it is interesting that Sikhs were most influenced by the Frontier region.