>As one who stammers, I've had to abruptly change my sentence struggle as I couldn't say one word or clauses, which can of course come out as nonsensical. I haven't heard a lot of Biden's speech (I'm not American) but the possible difference here is that if I adjust my sentence and it ends up nonsensical or not what I meant to say, I will then immediately repeat a complete adjusted sentence (or phrase, depending on what the nonsense was) that does make sense. If someone isn't doing that, or in some other way ensuring the listener understands what was meant, then *maybe* it could be a sign of another issue. (But I say this as a fairly mild/intermittent stutterer, I understand not everyone can do this if their speech is much worse overall than mine).