OP:advise your friends to just not irritate people in public by being obnoxious and they'll be fine. Also no hand-holding or public kissing. But that's about it.

As to ideas about what to recommend your friends - they will arrive at around 1200. This is perfect as immigration will be deserted. I would recommend leaving the airport and booking a hotel - as DYWKIA states, they are plentiful with all sorts of budget ranges.

If this is a revenue J ticket, not an AS award, then they may be able to avail of chauffeur drive at DXB - but if not, taxis are plentiful (and Uber works in Dubai). Would not recommend hiring a driver.

Go for lunch then sightseeing, or sightseeing then dinner. Or napping. Pretty much everything will be indoors or close to indoors - by which I mean, air conditioning. Long pants only if you want to go somewhere relatively nice - but since they should have a hotel room, this should be no inconvenience!

They will have boarding passes issued in DFW for the onward connection, so they only have to be at the airport 1 hour before departure and pass straight through a dedicated part of the terminal - the formalities are extremely painless for J pax. I would recommend 90 minutes if they want to see what's in the airport etc.