I think generally people who carry an external keyboard and mouse around along with their laptop still think they're using it 'as a laptop.'

Most laptops IME mostly get used on a desk whether with additional paraphernalia or not; 'laptop' gets used to describe the class of machine more than whether it's touching your legs or not.

If you meant literal in-lap use it probably would've been better to specify it, and if you didn't mean 'useless' entirely it would probably have been worth clarifying that since your questioning whether the recommendation was sarcasm rather suggested you -did- mean useless entirely.

Language is a pain, sadly, but I don't think lojban is going to win any time soon.