> These were prone to (relatively primitive) bus sniffing attacks, where you would hook up a Logic Analyzer to the bus, watch a regular boot procedure grab the disk key, and then use software like Dislocker to extract all data from a USB Live Linux or alike.

The TPM supports encrypted sessions, but they are opt in. See Parameter Encryption in the TPM spec. The issue is that Bitlocker doesn't use them for whatever reason. If Bitlocker turned on encrypted sessions, it would be not possible to sniff the key. It's crazy that Microsoft keep things insecure.