Incorrect, it is not present at all. Flash Reviver doesn’t use Flash 10 for a start, but more importantly, it modifies Flash so it is an entirely new library, which can only used by Messenger. Messenger itself won’t load the winks unless they’re digitally signed by Microsoft. It completely eliminates the security issue.
If you just install Flash 10 on your machine, any application, any script, anything on your machine, can execute Flash. I wrote more here.
But to add to that, a security researcher friend of mine was joking with me earlier today about how he could search for people using older versions of Flash like you propose, as with bitcoin at an all-time high, he could make some serious cash. Do you really think the professional ransomware criminals aren’t doing the same?
The basis of computer security is minimizing your attack surface as much as possible. That’s the core reason why Flash has been universally rejected.