Not only is turbo allowed, but it is actually potentially worse.
Does turbo make a lot of things easier and faster? Yes, but you have to be careful with it.
Text locking occurs when skippable dialogue is mashed too quickly, causing it to not be able to be skipped, and forcing the player to listen to the entire line of dialogue. You can observe an example of turbo actually losing me time in the cutscene just before clasko skip. Wakka's dialogue line "Lulu?!" is able to be skipped, but I mash it too quickly and lose about a second and a half. This is just one minor example.
Additionally there have been times where I've accidentally left turbo on and mistakenly cast a spell or used an item, losing me time and in more extreme cases, affecting the RNG tracking negatively.
What I'm using is a Fujiwork Kiwami controller, which is a ps2 (or ps1, I don't remember) controller that has various turbo speeds. Hold the turbo button and press the input you wish to enable turbo for. To clear all turbo settings, you hold select and then press the turbo button, which you will also be able to observe in my runs.
My runs are legitimate efforts, and if you think otherwise, try and find some real evidence to provide to moderators. (Sorry to break it to you, you'll find none.)
Do you sincerely think that if I was going to cheat with some kind of special input method, that I would leave the evidence in an onscreen input display?