The reason your Trump-aligned relatives and others like them are saying this "ensures his re-election" is because they're shocked and upset that Donald Trump has officially been held accountable for something.
Consider that a lot of Trump supporters (not the disgusting ones who go full MAGA), the people around you who think Trump is "an effective leader", think so because they support a conservative agenda and Trump was supposed to be the invincible champion of their causes; 'Telfon Don'. Supposedly, nothing could stop him from getting those "wins", not any of the scandals as a trash celebrity realtor, or during his primary, or during the Mueller investigation, and less and less ethics and reason matters because "by god our unpopular bullshit is finally getting through".
Well, something finally stuck, and this is quite a stain to have.
The MAGA crowd will go down with the sinking ship, because they are maniacs. But for some conservatives? I would hope this is where they get off this stupid ride already. If there's anybody who's gonna be divided, it's them.