I emailed the kind folks at finakits. This is what they had to say...
Q. When using your kits, should you bake your final product at 250 degrees, let cool, and repeat 2 more times? I've heard some mixed opinions on this.>>
A. you do not need to...but if you want...you can.>>
Q. Will it KILL the final product or diminish the potency?>>
A. not if you bake it for 15min at 250...any longer or higher temp may...>>
Final analysis: Baking doesn't kill your product and makes it safer to use, so bake it.