There's so much that's wrong with this idea that it is hard to know where to begin addressing it.

But, to take things from the top, your source appears to be referring to the idea that, for members of the Hindu faith, travel across open water involves loss of caste.

This concept was very widely believed by the British during the time of the Raj, so much so that it formed part of a penal policy designed to make the shipment of prisoners to penal colonies overseas – most commonly in the Straits Settlement, what is now Malaysia – a severe deterrent.

It needs to be stressed, however, that the proscription, as usually presented in western works, is very exaggerated. British understanding of Hindu belief was not always very nuanced, and while it's certainly true that travel could and did result in loss of caste, that loss was not necessarily, as the British believed, absolute and permanent – a mortal blow from which no Hindu could recover. James Kerr, in his The Domestic Life, Character and Customs of the Natives of India (1865) pp.263-5, notes:

It is very generally supposed in Europe that loss of caste involves trials and privations indescribably awful. The idea in men’s minds is, that a Hindoo who loses caste goes forth like Cain with a mark on his forehead, and becomes an outcast and a vagabond on the face of the earth. Some of our most popular writers have done much to give currency to this opinion. Whether loss of caste ever carried with it, in practice, these terrible consequences may well be doubted. Certain it is, that it no longer does so. In the present case, it amounts merely to this: the man who loses caste, places himself in a position which prevents those of his own circle from inviting him to entertainments, or being on a footing of intimacy with him. But in no case does he become an alien or outcast, shunned by everyone. The world at large transacts business with him much the same as ever… If he wishes to be restored to the full privileges of his caste, all he has to do is to submit to a pecuniary fine, to evince his penitence by giving a feast to some of the leading members of his caste, or to condone the offence in some equally easy way.

A moment's thought suggests that the British ability to transport large Indian armies to fight in campaigns in Abyssinia (1867-68) and indeed the First World War must imply that Kerr was correct in this assessment.

So there was no absolute "ban" on travel overseas, and in any case, the proscription applied only to Hindus and not to Muslims, Jains or Sikhs. That's significant, since most of India, in the seventeenth and eighteenth centuries, was ruled by the Muslim Mughal dynasty.

On top of that, of course, no ban on travel over water would have prevented Indians of any faith from travelling overland or from absorbing and utilising new ideas that came into the subcontinent from any direction; and India had plenty of problems in this period, not least those of dealing with the activities and demands of European trading companies, that had nothing at all to do with any exchange of ideas or inventions that may or may not have been hampered by reluctance to travel by ship.