He could have taken all his general education classes in his first two years. Some people do that. In the first two years some/many (most?) take at least a few classes in their major to spice the drudgery of general ed. But for the sake of argument let's give him the benefit of the doubt and say he took exactly all the classes he needed in his first 2 years and completely satisfied his general ed requirements. He would then have two years left to satisfy his major requirements for one major. If he got the classes he needed exactly when he needed them (something as you know that is often impossible) for one major only and he left 34 credit hours short, then he left with a year early.
Walker may not be like most college students. He may have taken the classes needed for one major and had only the classes remaining for the other two majors. He probably didn't, but he could have done it that way.
Far more likely, he probably had a class or two remaining to satisfy general education requirement. Also he probably mixed classes from his 3 majors. If he did that it would be highly likely that he doesn't have enough hours in any of the 3 majors to graduate in 34 hours. He could easily have a year and a half left to graduate with one major. Those who have gone to college know that that scenario is much more likely.
It is my guess that Walker did not get booted from school. I suspect that in class hours he may appear to be a senior but in reality he left school as a sophomore or as a rising junior at best.