No. The user could still deliberately chooose to run a different back-doored encryption software on the same computer. The definition still holds.
The iPhone went there years ago. The situation on Android is tenuous. OSX and Windows both now both start from a secure boot mechanism. At this point it is still possible for a user to work around these things but this is now "at the pleasure" of the OS maker and not something the user actually controls. Removal of a couple of checkboxes is how far we are from losing user-controlled right to install software on any mainstream consumer supported OS.
So I am arguing that now that operating system manufacturers have forfeited their ability to say they cannot prevent the user from installing software, it is only a matter of time before it becomes legally mandated that they close off this capability, and deliver only software that is delivered from a verified (probably government licensed) channel.
i upgraded my home server few months ago. It was runing archlinux for 13 years. It was up-to-date, not some ancient codebase. Yet, the "new" 2y-old-tech motherboard/processor/memory combo did not even start / recognize the SSDs. Took me a week in debugging, and replacing the motherboard with another one. Exactly One check box in the BIOS/setup, yes, and your gone. The 2nd mb did have it. The 1st did not anymore.
have fun