Should I tactfully speak up right away when a co worker openly talks disrespectfully?

If they're not disrespecting you and you're not their boss, NO. It could backfire on you.

Write down what they said and have a chat with your supervisor about it.

If you have to take them aside and talk to them privately about it.

if it offends you tell him so you a have as much right to speak your mind as he does

Of course. Later - you might as well forget about it.

I would. Nip it in the bud.

I normally tell them to shut it and get back to work. Only once I had to do that.

Just tactfully quit the rat-race.

No one likes a social justice warrior