Does it matter to a seller why someone is buying this system unless you are biased to see any Indian positive news within the lens of a bias.
India is not stopping Armenia to buy from Turkey, Israel, or anyone from the world. India is trying to expand its defense export to other countries. In this process, there is a buyer who is ready to spend even if it sounds strange for Armenia to buy long-range weapons. So rather than questioning to India, you should ask your friend Armenia about it.
Eventually AZ will override Armenia due to the fact that it is allied with powerful nations such as US and getting arms of Israel. But that does not mean, other nations would not do any business with smaller countries.
Did you ever ask why China does a military joint venture with Pakistan?