I don't think Feilong really got "propped up". He was exposed pretty early as someone who just lucked into a time period when Stark had sold off his company and spent the money buying up all sorts of dangerous weapons on the market.
Feilong was the Dragon https://tvtropes.org/pmwiki/pmwiki.php/Main/TheDragon of the real big bads, something foreshadowed heavily in his name and powerset. Feilong literally means "flying dragon", and he has a dragon's firebreath.
I do think Duggan made some big mistakes in his run, but not foreshadowing that Feilong was merely an attack-dog with delusions of grandeur was not one of those mistakes.