If Elon decides to drop his bags today, the market will suffer a massive tragedy, perhaps even greater than the last Covid 19 dump.
The future of bitcoin is something to keep an eye on, especially now that Elon Musk leads the pack of billionaire wolves.
Elon said that the remaining bitcoin purchases of Tesla was for long-term holding. And, let's not forget that Elon already sold in the past, so if they were to sell again, I'd guess that the market effect wouldn't be too drastic as you're describing.
And as far as I can remember, they've sold before to "test the market liquidity", so I guess they've got the results they wanted already and most likely it passed on their side.
So yeah, they are here for the long term, and it has proven a good move on Tesla and all other companies that decided to hedge there assets on bitcoin and put in on their balance sheet.