Answer:
If the only access allowed is "viewing" the entity's account and activity, there would be no problem that I can think of. However, when "viewing" should never be allowed to expand to the point where the individual can move money between individual and entity accounts. That sort of activity can allow a creditor to "pierce the corporate veil" and seize assets of the LLC's owner to satisfy obligations of the LLC, and that is one of the principal reasons that LLCs and corporations are created -- to protect the assets of the owners.