I think you are definitely right in creating boundaries, which is something I do too, when selecting clients. I purposefully won't see guys under 25 as I find they just want to rattle my bones and screw me senseless for the full duration of the booking, even though I am not far off that age, I find it horrible!! I could be losing out here, but that's my experience of it. I do have other reasons for not wanting to meet younger clients too, like I might actually know them or they find it hilarious to out me if they see me in public.
However, something I have found is not to stereotype people when they are communicating with me. For example, I had one guy who kept writing "babe" in his messages. I hate this. I find it rather degrading and wouldn't normally meet with someone who uses phrases like this as I believed them to be neddy / chavvy / wankers. But I met with him regardless as everything else he was doing was correct. When I met him, he couldn't be further from a typical "babe caller". He was a respectable business man, very well educated and was extremely polite and courteous towards me. I couldn't understand why he kept calling me babe! Then I realised, maybe he thought he had to speak to me that way???
Anyway, the moral of that story is: not to put people into boxes. Do not force yourself to meet with people you are not comfortable with for money's sake but I think you are right in maybe being less restricting in client selection, if that's the way you want to develop your business.
If you did not want to open up your target market, then you have to look at your marketing strategies and possibly expanding them to reach your target market? I have just been browsing through the post on where to advertise. So far I have only ever used AW and found myself to be very busy since starting 3 months ago. However, just to keep ahead of the game I have now drummed up my own little website and plan to advertise using other platforms. Good luck with whatever you choose to do.