Replace "spanish nationalists" by "everybody else" and you have it. The idea that the main language of a nation, the only that everybody share and knows, should be deterred from part of the territory is surrealist.
It's not the meaning so much as the choice of prepositions. When you say "deter X from Y", usually Y is the thing being reduced/prevented and X is the actor who is now less likely to Y.
So the use of "[action] deterred from [region the action might occur in" was surprising and possibly incorrect. If you'd said "[...] deterred in [...]", it would have been perfectly grammatical English.
It's a weird nit to pick in such harsh language, especially on a comment section that's more likely than the typical HN comment page to attract people who are not native English speakers.
Definition of deter
transitive verb
1 : to turn aside, discourage, or prevent from acting
she would not be deterred by threats
2 : inhibit
painting to deter rust
I have also seen "crime" and "war" given in examples of sense 2. To "deter the language", in sense 2, would be to deter speakers from using the language. You can sort of unify the two senses by treating "rust" or "war" or "crime" as willful entities - but in that case I don't see a reason you couldn't do the same for a language.
Do you actually fail to understand what pvaldes was trying to communicate?
Well, I know the general idea that he's trying to convey, since it's the same sort of message that I read in the nationalist press (e.g. El Mundo) day in day out, but I think if you intend to have a productive discussion you have to talk precisely, otherwise it's a waste of time. To say that a language is being "deterred" is not precise, it's vague and confusing, even if not technically incorrect (although I doubt that).
