Russian propaganda doesn't exclusively target the US. They also target their own citizens. Plus, we don't know that whomever took over your account was Russian, just that they were prepping it for activity in Russia. After an account is taken over they don't immediately start spamming and get themselves banned. They need to gather thousands of accounts before they launch attacks so the anti-spam bots don't shut them down. You can't effectively multiply a message with just a handful of accounts.

Of course at some point the guy who hacked your account fucked it up and blew a bunch of his accounts. At this point Twitter thinks you're just a bot account and doesn't care what you have to say.

Most common other ways to take over an account involve calling tech support and telling them you lost the password and the email account.