The longer the russian's know or have the exploits without the NSA knowing they've been compromised, the longer they can hold it against them. -- Imagine you've hacked a bank network vs robbing a single bank, and every week you take 1 penny from all users without anyone knowing, and do this for 3+ years... you'd get a lot more than a one-off bank robbery... That's the long game that Russia would play - milk it for every ounce of use, and keep it totally secret.
They get nothing from exposing it, hacktivists on the other hand get a lot more, and are more boastful about their exploits.
Hold what against them? The exploit? That makes no sense.
The Russians do not use the exact same set of tools that the NSA does. Sure, they may have discovered some of the same exploits, but the two do not have the same "toolbox" strictly speaking. Releasing a set of tools used by the NSA doesn't mean that Russia loses access to the systems that they have compromised...
They get nothing from exposing it, hacktivists on the other hand get a lot more, and are more boastful about their exploits.