In a meeting with back-end team (Bhakti, Junhao, Kaushal, and Mohammad) there where 3/4 votes for Django.
Human Resources
Python is the most famous programming language, so team can always hire new members. According to:
https://bootcamp.berkeley.edu/blog/most-in-demand-programming-languages/
https://www.bitdegree.org/tutorials/most-used-programming-languages/
https://technostacks.com/blog/most-popular-programming-languages
https://www.simplilearn.com/best-programming-languages-start-learning-today-article
Also so many junior programmers (which are more likely to join volunteer projects) use Python in their beginning.
Python benefits
Huge community behind
High performance
Frequent updates
Cheap hosting
Human readable syntax