"Commercial" - such a swear word for some isn't it? Maybe, just maybe, he has food to buy, a mortgage, a utility bill to pay, and fancies the odd night out. Maybe he's also thinking the average peak lifespan for a "pop star" is a few years at best and he needs to make hay while the sun shines?
Or, just because he's a musician, isn't he entitled to earn an honest buck as he sees fit?