The question asks whether this use of punctuational ellipsis is "grammatically correct".
However, this is not a question of grammar at all. It is rather an issue dealing with English writing, not with the English language per se. Writing is just technology; it's (real, spoken) language that has grammar. English punctuation, in particular, is not fixed by any agreed-upon rules, but rather is employed quite variously, as it always has been.
The fact that (real, actual spoken) English grammar is not taught in Anglophone schools has resulted in people using the word grammar to refer to just about anything they were supposed to learn at school about writing that they're unsure on -- including punctuation -- and also to use the term "grammatically correct" to refer to the imagined solution to their puzzlement about it.
I would suggest that, if a writer believes their reader(s) will understand their phonotactic intention in using an ellipsis, then the writer should go ahead and use it. "Correctness" is of no consequence here; effectiveness is.
For instance, I was puzzling the other day how to represent the intonation I wanted in the mind's ear of a reader, with a post that started out: Well ... I guess you could say that. I fussed with commas and other things and finally wound up using the ellipsis to indicate that the intonation slopes down for a while till the I is pronounced.
Note, this wasn't a pause; it was a longer-than-average well, with the final lateral resonant stretched out on a downward intonation contour. Any English speaker knows what that sounds like and what it means; the problem is representing it effectively in writing, which is preferable to smoke signals for representing English intonation and rhythm, but only just.