What would be the expected reaction if someone you liked non-romantically abandoned you in a stressful, literally life-or-death situation? Feeling abandoned personally as well as practically is inevitable even if they had a weak friendship. Ozaki's fairly despondent even when just the creole crew refuses to support him, and they're a group of decidedly less influential, useful friends than Seishin as the other head of the village is. Comparing his response to them (whom we presume he has no romantic feelings towards) with his response to Seishin, I'm not sure I see a significant difference from which I could infer anything beyond friendly affection.

An argument could be made that he's simply consistent in character (he honestly takes it remarkably well given we know he's prone to anger and hissy fits under stress) whether in love or not, but then the argument could be made for him being in love with any of the above, so I would still require supporting, differentiating evidence.