Now I checked tennis statistics. Since the beginning of their pro careers, this is status of their matches until their 32nd birthday.
Federer played 1116 won 908 win/loss percentage 81.4, minutes on court 112,716
Novak played 1039 won 859 win/loss percentage 82.7, minutes on court 113,251
Nadal played 1090 won 903 win/loss percentage 82.8, minutes on court 120,990
From the above we can see that Roger played just 77 matches more than Novak and 26 matches more than Nadal until their 32nd birthdays respectively.
From the above we can also see that Roger spent less time on the court than both Novak and Nadal. He spent 8.92 hours less than Novak and 137.9 hours less than Nadal on the court playing Pro tennis.
Therefore, we can't say that Roger was "older" because he played just 77 matches more than Novak and 26 matches more than Nadal while spending less time playing Pro tennis until the age of 32 than both Novak and Nadal.
That seem just as an unjustified excuse, I'm sorry to say.