I think I can answer this question.
Eating from toilet is not bad per se. However, it matters how long you are eating and what it is you are eating. What I mean is this. If perhaps you're eating a banana, you'd probably finish eating the banana or an apple, before you are done urinating. I think what you should consider here is when you have to flush the toilet. Flushing the toilet is equivalent to sneezing.
When you sneeze, particles, microorganisms spills everywhere. In the same way, when you flush the toilet, droplets containing bacteria are spread in different direction and if the food eaten is exposed, then consider it pretty much contaminated.
Generally, the toilet is not the best place to have one's meal. I mean that's what the dinning table is made for. So, even if you are eating and you are pressed and have to quickly go to urinate, you could consider dropping the food on the dining table, go take a pee and then come back. Or if you must, finish the food before going to urinate in the toilet. it's better to be safe than sorry and having to wait for few minutes would do you no harm. Also, it's been said that the handle flushing the toilet one of the most bacterial infested point in a house. It's probably contaminated with so much germs. So, if after handling the handle, you forget to wash your hands and you go back to eating your meals, you can have your food contaminated which in turn affects your health. So, generally, I would advise that you don't eat while urinating I hope this helps.
If you are truly so busy that your schedule dictates you have lunch while going to the bathroom I would imagine the stress alone is compromising your immune system. Therefore I would guess yes it is unhealthy.
It's weird AF