In the following sentence:
众所周知,简体字源于历史上人们自行简化的手书体,它是以繁体字为基础的,不能打着传统文化的旗号去否认简体字。
打着 means "hit the mark", according to Pleco. 百度词典 does not have the entry for the word.
I struggle to understand the meaning of 打着 in this context, which likely is either one of the following:
Unless you "hit" the flag of the traditional culture, you cannot veto the Simplified Chinese. (i.e. if you "hit" the flag, you could veto it; this is from 不能 and 否认, two negation words)
You cannot "hit" the flag of the traditional culture to veto the Simplified Chinese. (i.e. you cannot veto the Simplified Chinese by "hitting" the flag)
Or maybe another meaning?
I'm not sure if 打 or 打着 (is 打着 a word here or 打 + particle?) has the positive or negative connotation in this context to begin with... It is likely 比喻 in this context.