The DNC absolutely cannot condone assassination attempts, and it's absurd to think otherwise. The second they actually claim that it's a shame the gunman missed, it would be open season on every politician in office. The GOP would see a DNC acceptance of violence as a declaration of war, every last one of them would jump on the conspiracy that the Biden administration must have hired a truly inept gunman to make the hit, and before you can say "The GOP already condones violence" you'd have a dozen more assassination attempts on as many targets.
Republicans WANT a reason to pull the trigger. They WANT excuses to start taking shots at people they don't like. The last godamn thing you want to do is give them a reason to justify it. So no, the DNC denouncing political violence doesn't make them look like they don't care, it makes them look like they're the only ones fit to actually govern a nation.
Don't be silly, you can't make a gun out of a tennis ball. You have to make the tennis ball a grenade before the 2A fanatics will protect your right to take it into a political convention.