If you’re not actively using your Twitter account, you should probably close it.
Having a Twitter account that isn’t active just makes you look bad. Since many businesses don’t actively update their website with any content with a date on it, I will personally confirm whether a business is still alive by going to their Twitter account. If they haven’t posted in a few years, I assume to things:
1) They went belly up or
2) They’re too lazy to take care of their Twitter account.
In either case, I move on to the next guy. And your prospect will do the same thing.