Checked baggage through TSA carry-on security when late for check-in?

Question

Hi Travel Stack Exchange,

Recently on a flight from LAX-BNA, I missed the cutoff for checked baggages by 6 minutes (10:15am departure, tried to check bags at 9:36). Yet, the automated check-in system still allowed me to pay 30$ to check-in my bags but wouldn't let me drop it off. Naturally, the check-in agent refused to accept my bags and told me that I had to "find someone to deliver it for you". (right, like i'm going to do that with 10 minutes before the gate to my flight closes smh).

Anyway, I asked him if I can gate check my bags and he said that TSA won't let me. I also asked him if they could put my bags on a later flight (this happens all the time) and he said that the bags must go with the passenger. Instead, I ended up forking $83.70 for him to book me on a later flight.

Question: Does TSA care about the size of your bags when going through security if people can gate-check their bags "complementary of <insert airline>"

In hindsight, I should've tried to go through TSA with my checked bag and gate check it so I wouldn't have dealt with the bs of forking more money. Ironically for the rebooked flight, both my checked-in bag and carry-on baggage did not make it onto my flight, and as of the time of this writing, I'm waiting for BNA to deliver my bags to my door.

Note: this question exists but does not answer the question I'm seeking.

Answer 1

TSA has size restrictors (the grey metal rectangle) in front of their hand baggage X-ray machines:

(Source: Wikimedia commons)

If your suitcase can fit through the size restrictor; then you could conceivably bring it all the way to the gate. TSA itself doesn't list any restriction on the size of hand luggage - they defer to airlines, however most checked suitcases are too wide for the hand luggage x-ray machine -- and if it doesn't fit, they won't let you fly (chances are that even if you raise a fuss about the lack of TSA requirements on size, they'll ask to see your boarding pass, note that your airline won't let it on anyway, and won't let it through).

Even if you get past the TSA, the boarding agent at the gate could look at the suitcase and deny boarding if they thought you were somehow gaming the system or would cause a delayed departure. Allowing gate checked luggage is at their discretion. More importantly, it takes time to tag and load gate-checked luggage and they may be under pressure to not let the plane departure be delayed.

So after all that trouble, the gate agent may put you on a later flight after all.