I would've thought so. He's the best footballer in the world, I doubt he'd train suboptimally to maintain that position and all the money, fame and adulation that comes with it just to be more buff. I doubt vanity would have much of an impact.... he's already well up his own arse and let's face it, he is in absolutely brilliant shape and most women would drool over his body even if he's not as big as most people here would want to be, plus he's both tall and a good looking lad, not to mention the minor fact that he's a famous multimillionaire. Just look at Hugh Heffner, that in itself is enough to bag as many ultra-hot women as you want.
With the positions he plays in and his particular style of play, extra mass would probably hinder his performance, not help. Extra muscle might help him sprint, but he's constantly so active often throughout a 90+ minute match that extra muscle might tax his endurance. Not really a worthwhile trade-off.
I'd imagine he's the sort of bloke that would really be looking to add some serious muscle once he retires though.