Sri Chand was against sikhism is mentioned in The Holy book of Sikhs - Sri Aadi Granth.
As it is duty of Sikh is to preach the fact written in gurbani and also duty of Sikh to agree on it.
As per Gurbani Satta Balwand Vaar (Angg 967),
ਸਚੁ ਜਿ ਗੁਰਿ ਫੁਰਮਾਇਆ ਕਿਉ ਏਦੂ ਬੋਲਹੁ ਹਟੀਐ ॥
The Guru gave the True Command; why should we hesitate to proclaim this?
ਪੁਤ੍ਰੀ ਕਉਲੁ ਨ ਪਾਲਿਓ ਕਰਿ ਪੀਰਹੁ ਕੰਨ੍ਹ੍ਹ ਮੁਰਟੀਐ ॥
His sons did not obey His Word; they turned their backs on Him as Guru.
ਦਿਲਿ ਖੋਟੈ ਆਕੀ ਫਿਰਨ੍ਹ੍ਹਿ ਬੰਨ੍ਹ੍ਹਿ ਭਾਰੁ ਉਚਾਇਨ੍ਹ੍ਹਿ ਛਟੀਐ ॥
These evil-hearted ones became rebellious; they carry loads of sin on their backs.
-- Also it is mentioned
ਸਿਖਾਂ ਪੁਤ੍ਰਾਂ ਘੋਖਿ ਕੈ ਸਭ ਉਮਤਿ ਵੇਖਹੁ ਜਿ ਕਿਓਨੁ ॥
Guru Nanak tested His Sikhs and His sons, and everyone saw what happened.
ਜਾਂ ਸੁਧੋਸੁ ਤਾਂ ਲਹਣਾ ਟਿਕਿਓਨੁ ॥੪॥
When Lehna alone was found to be pure, then He was set on the throne. ||4|
Just because Sri Chand was son of Patshahi 1 does not mean he should be embraced.
He was just alike Prithia, Ram Rai, Dhir Mall.
Think yourself before commenting blindly under false devotion. If you are Udasi then there is no issue, Udasi is not Gurmat.