I don't think slave is a forbidden word. Maybe I was too strong in my own wording. I didn't mean "slave" specifically, but any word used incorectly, and especialy those with negative connotations, used as a quick way to "win" an argument.

>and it wasn't used in anyway that deviated from standard use.

Slave:[0]

1 a person held in forced servitude

2 disapproving : a person who is completely subservient to a dominating influence a slave to fashion/technology

3 : a device (such as the printer of a computer) that is directly responsive to another

4 : drudge, toiler

While 4 could have been the intent here (2 has a negative conotation for the slave) if we only look at it's ability to descibe the relationship between China and the US, looking at the whole sentence:

In other words, slave moved up the value chain and no longer wants to slave for their masters.

It is clear that 1 is being used here. We are using slave as both a noun and a verb, and describing the US as the master. I should also note that 1 is by far the most common definition, and other dictionaries have only that one when used as a noun.[1]

[0]https://www.merriam-webster.com/dictionary/slave

[1]https://dictionary.cambridge.org/us/dictionary/english/slave