I did in fact, later, give more detail (and I didn't give the detail in the first place because, frankly, I didn't think anyone would need me to elaborate -- I thought it was all pretty trivial information). It's basically that the fact that IR is line of sight, doesn't tend to have "trusted" devices, etc. causes IR to be more secure for exactly the reasons that it is less convenient.

Further, you may find yourself employed somewhere where BT isn't allowed to be used. And where they'll actively scan for its use (not just to counter external adversaries, as the Faraday cage idea would cover, but also from in-building adversaries). In that situation, IR is infinitely MORE convenient than BT ... because BT might cost you a job or security clearance, and IR wont.

But, the basic point is, BT has lots of security vulnerabilities that IR avoids, and therefore has it's own attractive aspect.