Sure. Why not?
I actually did this a few months ago as it got too late to finish a smoking session of ribs (2 AM is past my bedtime normally). The next day I threw them on the grill over medium indirect heat to warm them up, then sauced them up and sizzled them over direct heat for afew minutes a side. The guests loved them and couldn't tell they had been reheated.
I agree. I vacuum pack and freeze a lot of leftover barbecue meat. I almost always reheat on the grill.