Academe: I think the only way you would be able to convince me that tweed is not old manish is to point to a group of youth in China or HK that wear tweed and have not been influenced by the British (ie: living in Scotland).
Vox: I have not seen anyone in China or HK with what I could recognize as a Saville Row suit. I have been to the Row and seen their bespoke clothing.
I can tell you that if I did see someone wearing such a suit anywhere outside of the row, I would not recognize it. This may be
heresy but I cannot differentiate between a Saville Row suit and a well fitting OTR or MTM suit. I am not in the "know". The only thing I noticed was SR suits use very interesting fabrics.
RE: Fit; SR is not the only way to get a well fitting garment. There are elements to fit here than would go unnoticed in the real world. There are also elements of fit here that would be noticed in the real world but are praised here.
How old were you guys again?

j/k but, seriously, leaving the internet-ego argument behind, sometimes you guys seem so disconnected from reality. Tweed in among Asians in Asia? It gets pretty hot there. That might be a reason it would be considered costumey or old. In HK, the only ones who are in the "know" about tweed are those old enough to have been influenced by the British. The costumes are the ones wearing tweed in 30-40 degrees celcius.
Mustapha: Agreed - Tweed is a British thing and does look off. Those who can "get away with it" could probably get away with a lot of things.