The problem is that in most places speeding and driving on a suspended license are not felonies so I don't think we have the whole story as noted in the other posts.

He should have been given written conditions of probation which specify what he can and can't do regarding travel. Some conditions specify a person is not to go outside the court's jurisdiction without the court's permission. If the conditions do not prohibit this type of travel then that plus a written okay fron the probation officer should be good enough--getting it in writing helps to prevent any disputes over the matter. You just have to anticipate what ifs and if he takes this tact he should be covered if something comes up in the future regarding his probation; remember, he must continue to abide by all conditions of his probation which may include regular meetings with his probation officer--I don't know how long he anticipates being gone.