Hi,
I requested Ansuman to share his email conversation with Vishnu.
He gave only a very brief snippet.
From what was shared with me, it is impossible to form a clear opinion about the conversation. So the benefit of doubt should go to Vishnu.
The conversation goes like this:
Ansuman states that he will have to escalate some issue (which cannot be known unless the full conversation is shared) to the attention of WMF staff.
Vishnu views this as a potential threat, says this is against Wikipedia's Five pillars and says if such moves are made in future this can be held against Ansuman in a public platform (the nature of this platform is unclear. It could be even a open discussion in mailing list of META)
It is my personal judgment that neither of them have made any real threats of serious nature even though either party is bound to feel so in the heat of the conversation.