The top-knot also suggests a wearer of a Sikh turban.
Also, pre-partition, lots of Sikhs lived in the Punjab. Post-partition, lots of them were dead and the rest fled to India.
Same happened in reverse in the parts of the Punjab that remained Indian - the Moslems were mostly dead or fled to Pakistan.
A pretty terrible situation for all involved.
So - having a Punjabi name certainly doesn't preclude him being Sikh.