A lot of guys liked Nielson after his pre-season game vs. the Sens last year. But Bonneau is an upgrade as the bigger and potentially tougher guy for that role.
Jimmy is getting more experience and winning more of his fights each year (had a victory over Mirasty near the end of the year). He'll probably not ever improve enough to be a regular shift player, but he could become a part-time enforcer with a few more seasons under his belt. Granted he'll most likely be gone by then.