But 2. requires BELIEVING the lying Musk, so we can reasonably discount that without further proof.
Something besides Musk telling us it is so, because he is known to LIE excessively.
And dismissing the argument because Musk is an unreliable source is NOT ad hominem by definition. It is noting the characteristics of the person saying the "truth" as someone who lies EXESSIVELY. And thus being quite skeptical of what is said.
If you said he was smelly that would be ad hominem. Or ugly and short. Both ad hominem. But to correctly note the bad acting of the person involved and suggest that they may continue such bad acting (as it is in their best interest to do so) is definitely not ad hominem.
You really need to get your logical arguments in order.