I'm not sure what shyness has to do with the founders' product. If you're basing you opinion of the product on the level of extroversion of its creators, can I suggest that you're looking for the wrong thing?
At some point you need to "sell" your product, even if it's only to the sales team you're appointing or to a VC. If you can't then I warrant you'll not get the best deal for yourself and probably not enthuse others to help you produce the best product (for some value of best!) that you could.