Question:

What is the strongest opinion regarding standing/walking while eating?

Answer: 

عَنِ ابْنِ عُمَرَ، قَالَ كُنَّا عَلَى عَهْدِ رَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ نَأْكُلُ وَنَحْنُ نَمْشِي وَنَشْرَبُ وَنَحْنُ قِيَامٌ
It was narrated that Ibn ‘Umar said:
“At the time of the Messenger of Allah (ﷺ) we used to eat while walking, and drink while standing up.

[Saheeh Tirmidhi no. 1880]

Shaikh Abdurahman al-Mubarakfoori rahimahullah said:

“in this hadith is evidence for the permissibility of eating and walking. The Hadith of Anas mentioned in the earlier chapter indicates it is prohibited. So the Hadith of Anas is carried to mean a dislike and the Hadith of Ibn Umar means it is allowed with dislike. This is a combination of both Hadith.

[Tuhfatul Ahwadhi]

~ Faisal Ibn Abdul Qaadir Ibn Hassan