If a 20 year old kid decides he wants to leave a bad situation he is a quitter? Did you ever leave a job?Breakup with a girl?
Harrison can go where he wishes and no way should he be ridiculed for the choice he makes. At the same time people who are lucky enough to be in a good situation can flat out ruin it. If a young player thinks he made the wrong choice, and wants to be elsewhere, it's possible to handle things like a gentleman.
Having been suspended will always shadow Harrison (through the media if not his conscience) unless he eats some humble pie, returns to St. John's and re-establishes himself here.
If D'Angelo goes elsewhere and acts up it will be impossible for him to get out from under the label of troublemaker and Harrison's talent (in professional terms) doesn't yet approach a level that would persuade NBA coaches to overlook his attitude.
I think that coming back is DLo's best alternative if he wants to turn this significant negative into a positive.
For his sake and ours I hope that's the choice he makes.