Why is drinking the leftover water of Wudu while standing permitted and recommended, unlike general water?

Ablution (الوضوء): Etiquettes (الآداب) and Disliked Acts (المكروهات)

• Because it has no legal reasoning mentioned.
• Because it is specifically excused due to public necessity.
• Because the prophet's practice specifically established a blessing and recommendation (Mustahabb) for Zamzam and wudu leftovers while standing.
• Because the water is warm.