It is not so simple when it comes to JVs. The Greenpine was completely restricted by the US ITAR laws. Why do we have it then and why are we making our own modifications to it?
It is simple, while it is true that US laws won't allow export of existing technology, but there are no laws that prohibit the companies from developing high end technologies in the client's state.
For the company in question, it is double the R&D expenditure, but it won't be a problem if the client and the company can afford it and enough numbers are bought, which India is bound to order. You can say the seeker may end up being better than what was initially developed. After all, it is the same for Brahmos too and looks like FGFA is also headed down the same path. We have plenty of existing JVs which are working this way.
Entirely different if we are going to buy the seeker instead of developing it in India. Then what you said would come into the picture, but then India won't go for such a deal.