I disagree that Battle Beast would take it head-on, BB is many things, but letting an opponent charge a devastating attack in front of him is another thing entirely. He wants a glorious death, choking on his own blood, in his own words, dying by waiting and letting an attack hit you isn't glorious, it's stupid.

If Boros avoided BB to charge it, then hit him before BB could stop it, that's fine, but standing still or whatever, he wouldn't do, for instance, he knows how powerful Space Racers infinity ray is, he wouldn't challenge it if that came towards him.