i don’t know. Was it wrong for those who believed that Ted Kennedy may have been criminally responsible for Maryjoe Konepke’s drowning death and coverup but voted for him anyway because he was a Democrat and a Kennedy and shared their political view?First, let me answer your question directly as a a liberal Democrat: take the "may" out of it and yes indeed it was wrong for people who believed that Ted Kennedy was criminally responsible for Ms. Konepke's death and cover up to vote for him.
Second, why does it seem like so many people on the right cannot reply or answer a question without deflection and whataboutism?
Because it allows users to implicitly defend indefensible behavior while still feeling personally above it. If all parties are always equally bad, and everyone is tainted by association with them, then nobody (save the whatabouter) has standing to criticize anything and all things are permissible.
It's also incredibly flexible as a tactic. You can whatabout events that are only trivially equivalent - if people dispute it you've still succeeded in changing the topic, which is a win. You can do it by attaching the behavior of one or a few to vast political categories, same thing. You can do it with events older than the person you're talking to, like here. Even if the behavior is genuinely unprecedented, you can just flat make up an alternate reality where the other side totally did the same thing and supporters will cheerfully whatabout that, like we saw with the obstruction of the last Supreme Court seat.
Basically the more rot a powerful group has, the harder it becomes to defend their actions on their merits, and the more appealing this becomes, enabling more rot. It's not a coincidence the Soviets were notorious for it. And unfortunately I expect it'll get worse before it gets better. Despite being much more prevalent on the right you still see it everywhere, and if both sides ever fully embrace it then nothing's off the table.