I think you would want to purchase MC21 from jriver.com and then purchase the TVPlus add-on from Kickstarter.
It would actually make a lot of sense for those who purchase the higher priced Kickstarter options to get immediate licenses for MC21 and then get the TV Plus package later when it's ready. Those who are going with the more expensive options are typically going to be new customers as those of us contributing just for the TV Plus portion presumably already have a license. As Kieran suggests, getting the license now would give those new customers a chance to get up to speed with JRiver while they wait for the TV Plus option to be finished. Even if many of those new customers can't use the TV functionality without TV Plus, they can start using MC for the rest of their needs and go through the bulk of the learning curve while they wait. And those purchasing the more expensive option are also going to get you closer to fully funding the Kickstarter, which is usually the point of having the higher priced options.
What would be the reason(s) for not giving those who make the larger contributions licenses right away?
Edit: I'm not overly familiar with Kickstarter, but my understanding is that if the project reaches it's funding goal, all the backers' credit cards get charged when the time on the Kickstarter expires while if the project does not reach it's funding goal, nobody gets charged anything. If the project reaches it's funding goal, it would make sense to provide backers who went with the more expensive options with their MC licenses sometime soon after they are charged and then deliver TV Plus to them when it's ready at a later date. This gives the backers something to show for their contribution, while JRiver gets the funding it needs to proceed with the project.