It is wrong.
Hinduism accepts anyone who believes in Hindu philosophy and
religion.
In the medevial age, the conservative sentiments and casteism
which affected and influenced Hinduism, denied people to adopt
Hinduism but later, Reformers like Swami Dayanand Saraswati, who
founded Arya Samaj and his follower Swami Shraddhanand started
Shuddhi movement to convert back the Muslims and admit them to
Hindu dharma.