The reason for the cancelled landing clearance is stated in one of the links in the first post. Probably this one:
https://avherald.com/h?article=4ae9377c&opt=0
I don't know Mumbai airport, but
AFAIK, the normal procedure when approaching reserve fuel while in a holding is to divert instead of declaring an emergency. Usually, with correct flight planning, that should be the safest option. However, when you arrive at your alternate and get told, "you can't land, we're full", things get interesting.
On the other hand, you, underfire, AFAIR are a professional pilot and should know better than me... ;-)
(Disclaimer: I'm just an SLF)