I am surprised by people who will resist an idea solely because it wasn't their own. There can be a sort of mindless solidarity in which they label anything from outside their tent - be it outside themselves, their team or their department - as suspect.
Let's take it to an extreme. Who cares if the most obnoxious toad in the room came up with the idea so long as it is a good idea?
But, the idea-blockers sometimes reply, if we adopt that person's proposal, then he or she will gain in status or strength and we can't have that. My answer is: Go fight your turf wars somewhere else. Adopting the other person's good idea associates you with the good idea and it puts the emphasis on doing a good job.
As for the toads, not all brilliant people are pleasant. If the individual is going to be around anyway, you should at least benefit from the experience. Ignore the croaks. Snag the insight.