They have mentioned that the Company will ship the product directly to the winner. Quick Heal is based in India, I just checked their e-store, they have an option to send the installation media to Indian residents, but they don't offer shipping to other Countries. So that could be the reason for the restriction.
Shipping a low cost boxed product, such as an Antivirus, to other Countries is expensive. Although I don't think this would be the case with Quick Heal, surely a reputed Company will prefer Customer Satisfaction over a few bucks.
Also, some softwares have region-specific licenses, Kaspersky for instance, have regional licenses which you cannot use from other Countries. Perhaps, Quick Heal have such a system too.