I wasn't necessarily saying it would work, just that I saw it as a possibility. Depending on how Andalite hooves absorb the nutrients, it's possible. I highly doubt that Andalites would have stomachs, as pure nutrients are pretty much as digested as they can be. Therefore, I assumed that the hooves absorb the nutrients directly into the blood stream, to be absorbed in different areas of the body. I figured if that's the case, Andalites may be able to replenish their cells with oxygen for a short time, at least.
Something that we have to remember is that the Andalite respiratory system is nothing like our own. Our oxygen is taken from the lungs and absorbed into our red blood cells. Hence, why blood is red. Andalite blood is green, meaning they have no red blood cells. We don't know how their cellular chemistry is orchestrated, hence we have no bearing as to how the oxygen is absorbed into the respiratory system.