I think this is an awkward way of saying they tried to add an abstraction on top of their AWS dependencies so that their services would work on Azure without a refactor.
Also, this reminds me of the time Microsoft bought Hotmail, and couldn't port it to WinNT. They had to leave it on its BSD variant for a long time, NT couldn't handle it.
I'm surprised it can today.
Arstechnica forum discussion on the topic in 2001: