The secession alone, or the federation-andorian glacial relations alone, or the andorian terrorist alone - perhaps not.
But together, they corroborate quite fine, they form a clear trend - and it was before this book, which drove home the point with the subtlety of a sledgehammer.
But...this 'trend' - in the end, it's only a few isolated incidents. Surely not important, yes?:
One needs to keep in mind that the trekverse is fictional - there really are no andorian - or otherwise - developments beyond what's established in the books. There aren't billions of unsung beings living their lives in the federation or on Andor or in the klingon empire, etc; suns burning or planets rotating other than in the authors' - and our - imagination.
What the authors choose to establish, even if only a sample of the whole - that sample is representative for for the state/trend of the whole. In this case, the authors chose to make the andorians as nasty as possible (with varying degrees of subtlety).
Were there only samples (until the last book)? Yes. But, in a fictional world, mathematical probability does not apply. The picture the authors consistently paint IS representative - despite it only depicting a small sample of the inferred worldbuilding.
Dukat was not the only cardassian depicted; Duras not the only klingon; etc. The scenarists/authors always depicted counterpoints; the samples included in the picture showed the other side of the coin.
Not so in the case of andorians (have no fear though, the token andorian, helping to save his world, will soon appear).