On the way Yehoshafat stuck by Achav, even when it came to the reliability of his shechitah, despite Achav being guilty of worshipping idols. Note the relationship between the king of Yehudah and the king of Yisrael, despite the divine among the tribes. Plus, the ravens who brought Eliyahu (Elijah) the Prophet his daily bread and meat... ostensibly from Achav's slaughterhouse (so how can Eliyahu have eaten that shechitah if it weren't acceptable? But he's really in a different reality). Plus, what if these ravens were people, not ravens? Also, a return to the Kutim/Samaritans - how it was determined to reject their shechitah after all. Plus, God protects righteous people from inadvertent sinning - or, in this case, not eating meat that wasn't slaughtered properly.