[michaelt]

Depends.

You can set up 'measured boot' so the TPM will only 'unseal' the disk encryption password if you're running a certain version of your BIOS, a certain set of Machine Owner Keys, a certain version of shim, a certain kernel, a certain kernel command line and so on.

Very few normal users do this because it's a great deal of effort/risk for very modest security improvements. But the option is present - it's sometimes used by big corporations making TiVo-style products to lock out the owners from messing with the hard disk in the manner you've described.