These are Adobe's concerns, not mine. I don't work for Adobe, but I'm familiar with Flash and have talked to Adobe engineers before. And it's not an easy call

These are Adobe's concerns, not mine. I don't work for Adobe, but I'm familiar with Flash and have talked to Adobe engineers before. And it's not an easy call to make: keep in mind how many computers have Flash installed. If open sourcing the project would double the rate that vulnerabilities get found and exploited, that's a real problem for Adobe. Trusted partners already have the Flash code and report security issues.