Hi,
It's a requirement same as ms account/ onedrive where the bitlocker key is supposed to be located.
Pretty good ransomware to make a ms account seems to me lol
Bitlocker is only enabled in three scenarios:
1-You enable it (meaning you go to the corresponding Control Panel/Settings area and enable Bitlocker)
2-It comes enabled from the factory (the case with at least some laptops)
3-It's enabled by Group Policy / Active Directory (important if you're using Microsoft 365 provided by your employer/education institution or any "enterprise" environment)
Bitlocker is never enabled "by itself".
Also, I always install Windows the way Microsoft intended (i.e., with TPM and Secure Boot enabled, with no bypasses/adjustments/hacks of any kind), so I can confidently say that nowhere during the process you're forced to enable it. In fact, I don't recall that I was ever asked to enable it to begin with, and it has stayed disabled the whole time.