A clarification on that point: OpenBSD's bluetooth stack was unmaintained and removed due to code rot; it's not that bluetooth as a protocol is inherently insecure.
> it's not that bluetooth as a protocol is inherently insecure
Bluetooth is a ridiculously complex protocol. Complexity is the enemy of security. There's no fixed threshold beyond which complexity makes something "insecure", and Wi-Fi and even USB aren't exactly simple (both have had their share of implementation exploits across operating systems), but AFAIU there's a strong sentiment that Bluetooth is far too complex for the benefit it brings, which perhaps explains why OpenBSD's stack was unmaintained.
Course, now we have Bluetooth: Wired Edition with USB-C layering many different optional protocols over the base transport. I understand the rationale, but I fear it means the days of "just works" USB may be coming to an end...
Bluetooth is a ridiculously complex protocol. Complexity is the enemy of security. There's no fixed threshold beyond which complexity makes something "insecure", and Wi-Fi and even USB aren't exactly simple (both have had their share of implementation exploits across operating systems), but AFAIU there's a strong sentiment that Bluetooth is far too complex for the benefit it brings, which perhaps explains why OpenBSD's stack was unmaintained.