Does the hadith you mentioned about the incident of the banner being taken from Sa'd ibn 'Ubada on the Day of the Conquest of Mecca indicate seeking help from other than Allah?

This story was mentioned in biographical books but was not authenticated. This type of seeking help is not forbidden, because it falls under seeking assistance from a creature in what they are capable of, which is permissible as stated in the Almighty's saying: ﴿So the one from his party sought his help﴾. As for seeking help from a creature in what only Allah is capable of, that is polytheism that expels one from the religion, due to the hadith: "Indeed, I am not to be sought for help; rather, Allah is to be sought for help."