Oh, I love the idea behind this! It makes me think that something bad happened to Star Swirl because he didn't make friends, so Princess Celestia will make sure the same fate doesn't befall Twilight. Beautiful comic!
Shortly afterwards, Starswirl casts that spell, switching everypony's CutieMarks. And a few days after the CutieMarks all got switched about, more CutieMarks began sprouting on ponies' bodies. Thus the Cutie Pox was introduced into Equestria.