There are arguments for and against.
My first thought was "Who cares", the comment is coherent and fine, and these comments tend to be quite short lived.
Then I remembered that they are not always short lived.
And that our names are on them.
And I "doubt" changing it would entail great deal of work.
I know, there is a huge todo list - I sympathise with that, but "status-declined" is different to "yeah we should do this, could be some time though, perhaps 6-8 (or longer)".
I can only presume the current message comes from a time long ago when the site was a baby, and such functionality was plumbed in quickly - "Ah, that works, that'll do, it's fine".
Whereas now, Stack is an extremely popular and large collection of sites, and strives to be grammatically correct in all places.
The low quality post review choices auto-generate comments in our name, and they're grammatically correct, such as:
This does not provide an answer to the question. To critique or
request clarification from an author, leave a comment below their
Capitals, full stops, even a comma in that one.
My conclusion is, I agree and I think it should be changed, and see no reason why it shouldn't.