He was responding to someone who was offering a disagreeing POV, on a public web forum that anyone can read or participate in.

In that context, typing "we need better language" implies identification with the whole audience, i.e. all readers. 'We' does not mean 'my group of political activists' when used in that way.

Hence why the correction is important. Especially given that he was advocating for the redefinition of language in service of a political ideology. If you are going to suggest that 'we need' to clarify and standardize the words we use to refer to things, then you should probably be extremely precise with your own language, no? Otherwise you are just being a patronizing e-tyrant.