You should never bring anyone on the team unless you feel they are awesome and will add value. I believe the first 12 team members will dictate the success of the company.

That being said, you can bring in team members and give them equity that vest over 4 years, so that there is no risk to your company if they don't workout. So if you feel you need the accelerator to be successful, do what you go to do to make it work, without loosing control of the product, direction or major equity (as you'll need it for future rounds of funding).

So if you can negotiate the terms to be entrepreneurial friendly from the incubator, and get their money - then do what you need to to to be successful ... even if they aren't happy - you're the entrepreneur, not them - which concerns me a bit that they are mandating you get people on your team that you don't want/feel you need.

Hope that helps.