Guru Hargobind, Guru Har Rai and Guru Gobind Singh were hunters. Why are there such vegetarian Sikhs?

I will comment on Sikhs being vegetarian or not. Guru says
ਮਃ ੧ ॥ਮਾਸੁ ਮਾਸੁ ਕਰਿ ਮੂਰਖੁ ਝਗੜੇ ਗਿਆਨੁ ਧਿਆਨੁ ਨਹੀ ਜਾਣੈ ॥ ਕਉਣੁ ਮਾਸੁ ਕਉਣੁ ਸਾਗੁ ਕਹਾਵੈ ਕਿਸੁ ਮਹਿ ਪਾਪ ਸਮਾਣੇ ॥AGGS 1289-90
Ma 1 || Mas Mas Kar Murakh Jhagarre Giyan Dhian Nehi Janai || Koun Mas Koun Saag Kehavai Kis Meh Paap Samane ||
Guru Nanak discredits the duality of vegetarians who oppose eating meat. Guru Nanak says that these people have their priorities confused. They fight for the virtues of not eating meat, but do not spend their time in contemplation of God. He says that every living thing is life, if one is killing an animal or a plant, he asks can the vegetarian please tell him where the sin lies if he is killing living things, be they plants or animals?
ਜੇਤੇ ਦਾਣੇ ਅੰਨ ਕੇ ਜੀਆ ਬਾਝੁ ਨ ਕੋਇ ॥ AGGS 472
Jete Danae Ann Ke Jia Bajh N Koe ||
No one is a pure vegetarian because there are living beings in water and every grain of food.
Gurmat says we should not fight if meat eating is allowed or not. No one is pure vegetarian. It is up to the individual if one chooses to be vegetarian.