First, I didn't see you say anything about trying to start it with the remote start when this happened. Did you try that, and did you get the same result as turning the key?

Second, I don't trust aftermarket remote starts because they seem to be able to do weird things when they fail.

My son bought a used 2009 Corolla with an aftermarket remote start. Within a couple months his battery began to get weak and eventually failed. Replaced that. Later, he told me it made a weird sound when he started it. My troubleshooting boiled it down to the starter staying energized after the engine started and the key was released - usually for just a second or two, but long enough that the engine was spinning the starter pretty fast. Had the starter diagnosed and replaced at the dealership.

During the above-mentioned troubleshooting, I had my voltmeter (ammeter) inserted into the circuit looking for a parasitic drain, and saw 200-250mA, fluctuating. Then the meter pegged a couple times, and its internal fuse blew. A couple minutes after reconnecting the battery, the starter energized briefly. I removed the covers from the the steering column and found the two heavy-gauge wires with 30-amp fuses on them, and removed the fuses. Problem solved, including the parasitic drain.

As far as I can tell, this thing had been actuating randomly for some time, or else had developed an intermittent internal short or something.

If I were you, I'd identify the fuses for the remote start, just so you know where they are. Make sure you can start the truck with those fuses removed. Then, if this happens again, you can remove the fuses more quickly and try starting. I know your symptoms are different from mine, but removing those fuses (and unplugging any other cables from the remote start) will at least electrically remove the remote start from the equation.