Wouldn't it be public anyway whether Tesla holds Bitcoin or not? As a publicly listed company they would owe that information to investors/potential investors if I am not mistaken? Especially as Bitcoin is a highly speculative asset I would think that owning Bitcoin would at least require a note in their financial reporting.
"Operating income increased substantially YoY mainly due to vehicle volume growth and cost reduction. Positive impacts were partially offset by ASP decline, growth in operating expenses, lower regulatory credit revenue, additional supply chain costs,
Bitcoin-related impairment of $51M and other items"
This was written on telsa financial report of Q3 this year, they mentioned bitcoin in their revenue income stream.
Reference :
https://ir.tesla.com/#tab-quarterly-disclosure