LOW BATTERY. Exactly. Hal comes off as an idiot because he doesn’t think before he speaks, but that does not mean he doesn’t think at all. In addition, and this is more of my own meta than it is something rooted in canon (though i like to believe it has some truth to it), Hal would rather others perceive him as an idiot because it decreases his chances of letting others down - something he’s terrified of doing. The dumber people think he is, the less people ask of him/expect of him, creating fewer opportunities for him to fuck up, because he does enough of that already.