They aren't. So they are themselves either 'not very smart' or the contributions from 'open sourcing' is not actually very valuable. I think it's the latter.
But, as is often the case, decisions that are optimal at the margin can often lead to suboptimal outcomes in aggregate.
I'm not convinced that's the case in IC fabrication, but its not impossible.
In terms of a trade war this has all the downsides of dumping products on the US firms with none of the downsides to the rest of the economy outside of the very top end of the supply side.
They open sourced their fabs, and random farmers on collectives would come home (while starving) and make improvements in fab technology by candlelight.
If only they had you to guide them, with your advanced knowledge of economics, trade and process technology.
Unless you want to talk to me about the fabs in Portugal and Mexico in 1990 when compared to the ones in Bulgaria and the USSR you're making my point for me.
Communism is great if you like hunger and oppressive stupidity. "But it's never really been tried!" - No, it has: it is fundamentally incompatible with freedom and/or intellect.
Nobody is buying what you're selling, champagne socialist.