How does one 'poach' a member?
Don't users typically post on sites they enjoy posting on?
The free market system would suggest that consumers select products they like, and given that forums are generally free, the decision of consumers to post on one forum vs another certainly would fit in that category.
The Indian users that post on Pakistani forums do so because they like engaging/debating with Pakistanis, and they enjoy the 'product'. I have to say, despite my current differences with PDF, they would never show the kind of response to new members (of any nationality) that you have shown here, and that is why Indians continue to post there, and return to post there despite infractions and bans. If you don't create a relatively comfortable atmosphere for Pakistani posters to post, then you will have no Pakistani posters, and those Indians that relish debating and engaging with Pakistanis will always go to other forums where they can do so.
Unfortunately, the PDF management also buys into this philosophy of 'other sites poaching members' (also an issue I disagreed with them on and one that played into my decision to resign), which is why my account at PDF was disabled after I resigned.
As a business in a free and open market, the goal needs to be making your product better and more attractive to more consumers, because otherwise the WWW offers plenty of other products for consumers to move to and the means to find those other products. Consumers are not 'poached' by other sites merely because those sites exist and advertise, but because those sites offer a product that those consumers value more than yours.
Cheers.
AM