It even says in the policy you are quoting in Spyderco's sole determination. Not the determination of the BladeForum self-appointed warranty police. How is it you determined he caused the cage to break, especially in the absence of any pictures?
To the OP, pictures would be useful. I'd certainly take any of my Spyderco's apart if they became gritty to use. If parts broke (especially the one plastic part in a mainly steel knife), due to my fault or not, I would still expect support from the company. If they wanted me to pay for a new cage, so be it. But I doubt I'd buy another product from them if they said tough luck like some of the jackasses in this thread are saying. I would contact them, I suspect they will make it right even if you have to foot the part bill.
You also might post a picture if it's still apart. I can't imagine needing or using Krazy Glue to re-assemble. Maybe a dab of grease if I needed the spring not to fall off the little strut while re-assembling or something. But I've never taken a Manix apart.