In all honesty, Panjabi Sikh insularity plays a part in all this. But if you look at the basis of much of the past intertaction that this community has had with the world, it is at least partially understandable (not excusable though).
Over the last few centuries Sikh people have been targetted for annilation or wholesale slaughter by successive governments (i.e. Moghul, Congress). Attacked by hordes from Persia and Afghanistan. Tricked into losing their hard fought over kingdom by the British. Left to face slaughter again when the British decided to up and leave India and partition their homeland. Treated as second rate citizens in a new country they made dispropotionate sacrifices for. They have also at times experienced racist and hostile receptions in newly settled lands.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=25257Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=25257
Conversion I think has become a dirty term in Panjabi Sikh circles because of their own corporate experiences at the hands of others who seek to convert them.
But all of this must be overcome and the good message of the Gurus must be made accessible for others. I am fairly confident that this will take place over time.