I think you have an argument that the late declaration should have been excluded because the case should have been submitted on the 3rd, no matter when it was actually reviewed or decided upon. To have any chance at relief, you MUST take this up by petitioning the appellate division for a writ BEFORE YOUR TDN. It won't work if you first bring it up on appeal. What county are we talking about? You may have to personally file the writ petition.
To understand why this is a violation of procedural due process and is not an exception, the difference between rule 4.210(b)(8) and 4.210(c) is important, as is the difference between "due date" and "time limits". Remember, first of all, that "due date" is basically ONLY the defendant's deadline during the various stages of the process, by definition (4.210(b)(1).) It doesn't apply to the officer's return date, or to anything else.
Under 4.210(c), the court can extend any due date or time limit (i.e., within x days), but this must be on the record (no reason needed). i.e., there must be an entry in the minutes, before said date, of an order extending it. 4.210(b)(8) says that failure to comply with any time limit does not invalidate the decision unless prejudice is shown.
Well, 4.210(b) is neither a due date, nor a time limit. It is a mandatory requirement - "the clerk must submit the case file with all declarations and other evidence received to the court for decision." Unless evidence shows otherwise, this is presumed to have occurred. Admitting any evidence after a case has been "submitted" is usually not allowed.
You need to go to (or contact) court clerk and get a copy of the officer's declaration. So you can see when it was dated, and when it was file-stamped. No mailing date, postmark, etc. matter here. A document is received as of the date that is file-stamped on it. If you mailed your declaration on the TBD deadline, the court can go ahead and ignore it. Why should it be any different for the officer?

