News flash: Trek has always used characters to "promote an agenda."
Now this was a little clumsier because its was Guinan and she wasn't herself but maybe a lot about her changed in the least 130 years and stuff about her will change in the next 300.
We don't know what 21st century Guinan was like.
They could've been a little less blunt or said something about a recent incident pushing Guinan over the edge, but using characters to promote an "agenda" is very Trek.
There's a difference between creating characters specifically to promote an agenda, and using old characters out of context to do so.