No he didnt, I took my existing bike along which has a 205mm head tube + 20mm headset cone up top. For a 58 frame that IS a tall head tube and im still using a 90mm stem. So you see, you cant size a bike based on stem length, you get the seat right and base it on that which is what the OP has found in this case. The most a different size frame will do is raise or lower the bars and at most mean you need to change the stem 1 size, but im already on the smallest possible frame with a long head tube. No frame would ever get me using a 120mm stem (just to satisfy your misguided rule of thumb) for example. Why do they make diffent stems if everyone needs the same length?!

EDIT: Actually come to think of it his first reaction when he saw me standing next to the bike was that it might be too small for me but then he agreed that he would have put me on the same due to the reach and agreed it was the best size frame for me. But oh no you know better because 90mm stems are for people who's frame is too big