IDK if you read what I wrote above, but the kids I observed throwing tantrum were autistic kids yes, but choosing to behave this way and able to stop it. The "trigger" for them would be they didn't get what they wanted, so they continued till parent gave in.
Right... so the behavior would, on the most obvious level, communicate their desire to "obtain" ...that they wanted whatever it was that they were having a tantrum over.
Behavior communicating something doesn't have to mean the behavior is involuntary.
On another level, it could communicate that they didn't feel comfortable without whatever it was that they wanted, and hadn't been taught yet to regulate those feelings.
On another level still, it could communicate a need for control and a learned ability to obtain control ("I'm going to tantrum to control this adult because it's worked for me in the past")
Etc etc.
In this case ultimately you'd have the best judgement, because you observed the behaviors directly. Meanwhile I'm just saying that there could be more to any given behavior than what is immediately apparent.
