You raise a valid point, but this attack is particularly alarming because it circumvents a TPM, which is a hardware module that was specifically designed to protect against evil-maid class of attacks, e.g. every iPhone after the 5S uses its Secure Enclave (a TPM) to enforce time delays between passcode attempts [0], so that a physical attacker can't brute force the passcode. (Incidentally, the attack described in the OP is reminiscent of some early attacks against the iPhone that used an HID device to circumvent passcode rate limiting.)

IMO, the continuing difficulty that the FBI has breaking into seized iPhones is proof that it's possible to ship a device with hardware that is sufficiently secure to mitigate against any physical exfiltration of data, but this is probably only possible because of the fully vertical integration of Apple hardware, firmware, and software (and even then - it's still a cat and mouse game, bugs will eventually be exposed, etc.). For open source software that runs on any arbitrary assemblage of hardware components, I suspect it's nigh impossible to achieve this same level of physical security.

[0] https://support.apple.com/en-gb/guide/security/sec20230a10d/...