He did indeed block Majima's opening strike. Kaidan answered with a one-two punch of his own. He tried to keep his fists within Majima's vision. He too held back some of his strength, so that if he managed to land a hit it wouldn't hurt that badly.

"I'm sure you've been asked this before, but how did you lose your other eye?" No reason why they can't talk and spar at the same time.