Making the MC unavailable for shooting scenes early in the game doesn't make sense to me from gameplay or immersion standpoints. The happiness mechanic already limits the number of scenes you can shoot early in the game, so I don't see where it's needed if you want to slow progression early in the game. Also, you've just started up a porn business, can't afford a studio and real male actors, your trying desperately to make the rent and your going to take time off??? Doesn't make sense to me.
Edit: Just to clarify, I'm talking about the random unavailability, not the unavailability because of low happiness. And combine this with getting an STD (even though wearing a condom all the time), it really slows progress to a crawl. This type of thing leads to save scumming
Edit2: It looks like the MC being unavailable to shoot scenes also prevents him from working. Have a case where it is 8:45 am, have 100% energy, 100% happiness, charisma of 35 and I get the message "If you cannot fuck you also cannot work. Rest." when I try to work at the bar. Only thing I can think that would cause this is the 'unavailable' status, so there is no way I can make any money. Since I have $758 cash, I'd be in real trouble if I caught an STD now.