A duplicant prioritized bathroom over starving to death

Harvesting is just harvesting. You don't set the priority of eating that way.
When it comes to going to the toilet and eating, your dupes will prioritize whichever was ready to do first.
If they got hungry first, but there was no food at that time, and then while you set them to go harvest for said food, they needed to go to the toilet, they will go there instead. Even after they have harvested, as that was the next thing in the queue.
You could try to control this if it happens again by disabling your toilet, and forcing them to do the next thing in the queue.

@SpoonsOnMyElbows Late reply here; yes, what you're saying is evidenced by what I reported. What I suggest is that duplicants be aware of dependencies, such as needing to harvest prior to eating (to avoid starving to death). Otherwise, even if I had wanted to micro-manage their biological needs, I couldn't directly tell them to "hold it"; disabling the toilet, as you suggested, would potentially handle this situation but would also be impacting all dupes and is clearly too inelegant to be the long term solution to these circumstances should they arise again.