Disinfection should apply to microorganisms, not multicellular creatures such as lice. If an insecticide was applied, that's a different story.
Your guys are very unlikely to have the lice get onto their persons unless they sit and lean their heads onto the fabric of the furniture (where they are more likely to be than the carpet).
They are less likely to lay on the floor, I would hope at least.
For their peace of mind, you can have them wear shoe covers, but they probably do anyway. Lice don't jump like fleas, so again just request that they not lay on the furniture or carpet.
If they are still creeped out over it, have them wear disposable gloves.