Issac knew he was being too hard on Kayla and should give Calan a chance, he was simply being protective of his sister. With his father gone, he had to take up the role of taking care of the family, and that included filtering those with ulterior motives or not. And those he deemed worthy of association.
However, it dawned on Issac that he was a big hypocrite considering he was dating a dark Fae horse shifter. His association with Maxi alone could endanger his family if found out. But then, he was an adult and could handle the consequences. Kaya was still a youngling and needed his guidance — in his eyes.
After Kayla's outburst, he decided to get to know Calan first before passing judgment, and what better place to do that than here? So when his ears picked up footsteps coming in their direction, he turned towards the source with great anticipation.