I would be the first to say that Joe Thornton has been an incredible surprise so far this season. I would also say that even knowing how well he is playing, I would still be very careful with his minutes.
Just because he is skating like he is 30 again, does not mean he can recover like he is 30 again. Im sure as the season progresses if the Leafs create a substantial gap from the other teams in the division they will probably start to rest guys like Thornton, Spezza, and Simmonds on a bit of a regular basis, but even in game every now and then I would try to lower his minutes.
He has been an inspiration so far, but Thornton, like most of us, probably wants to keep that energy for when it really matters. In the playoffs.