Should a traveler pray Jumu'ah prayer shortened and combined with Asr, or pray it without combining?

Jumu'ah prayer is not obligatory for the traveler, so he prays Dhuhr two rak'ahs, shortened. He is permitted to combine it with Asr, either by advancing it (taqdeem) or delaying it (ta'kheer), when there is a need or hardship. However, it is better to perform each prayer at its appointed time if there is no need to combine them, as combining prayers is not a Sunnah of travel like shortening them, but rather it is done out of necessity.