Yes it is. I do it all the time.
It is not the actual non-stick surface which is usually PTFE, the same stuff that is put inside many heart bypass patients. It is generally what adheres it to the pan that is the problem. If one has scratches or nicks that is when the "glue" can seep out.
I worked for T-Fal. I found out a lot of info about non-stick. I use a lot of T-fal and always have. I replace them occasionally when they show too much wear but I have not only all the frypans and saucepans but also the chicken fryer, 4 at dutch oven, 8 liter, 12 liter and the not-made-any-longer 16 liter stockpots.I also have an oval roaster, a rectangular roaster (both in the original gray T-fal that was pushed into the surface of the pan instead of being "glued" on), cookie sheets, cake pans, bread pans (American and European) and probably some that I forgot I have.
I sear with high heat all the time.