True, but Thomas wasn't yet a gc rider in 2015. He was already a decent climber, but no more a gc contender than someone like Van Aert is today. Once he focused on gc racing he never again contended on the cobbles.
Wiggins meanwhile completely stopped riding for gc after 2013 and became more of a TT specialist. Also, while he did get a top 10 in PR once, he was never really a force in his attempts there. I feel like if you name him you could just as well name Nibali, who at least had his shot at the Ronde when he was still a gc contender.
So I guess technically you are right that there have been TdF winners near the front of cobbles races, but really, none of those performances compare with Pogacars.