?

It's strange that this moment wasn't included in the event itself, but rather placed in the codex. Oh well, let's assume. One can still argue, however, about the ways to escape against the will of the nobles. (or after usurping power, like Lü Bu). But that's a separate topic. Other points are still valid.

Being in complete control of the symbiosis does not necessarily mean thinking clearly.

Lü Bu, in general, is not very capable of clear thinking, as I mentioned earlier. The horse incident fits very well with his modus operandi.