My flaxseed oil went rancid after like 3 months in the cabinet, so that part didn't work out great for me. That said, I've done the 450 oven thing on a couple pans and yeah it looks pretty for the first week, but mine got splotchy and started flaking near the edges once I actually cooked with it daily. Stovetop takes longer and it's more work, I'll give you that, but I can build up thin layers over a few days and they bond way better in my experience. The oven heat is also way past the smoke point of most oils, so a lot of that layer is kind of burnt on there instead of polymerized all the way through. Maybe your flax pan is newer or you got lucky with the temp, but give it six months of bacon and eggs and see if it still slides the same.

The "parlor felt chilly" so he torched it while you're still working, that's a bold move on his part. I've eaten that same soot sandwich before, nothing humbles you faster than looking like a chimney yourself. I just pull the rods and cap the throat now, beats scrubbing my face for a week.