If it is a smart team working on an interesting/challenging problem and you think you would enjoy it, then the fact that they want to flip the business should only be a secondary consideration.

Just remember to set your expectations correctly about cash/equity incentives: http://www.bothsidesofthetable.com/2010/09/06/how-to-discuss..., http://www.bothsidesofthetable.com/2009/11/04/is-it-time-for...