If it stops enough people around the world buying Apple products it will affect Apple's sales and revenue which will in turn affect their share price.
Like it or not homosexuality is still illegal in many countries around the world and causes hatred in many other countries. Cook has effectively outed Apple as an actively pro-gay company. Only time will tell to what extent this affects their sales and revenues. Right or wrong he's taking a risk.
http://www.networkworld.com/article...-have-long-been-champions-for-gay-rights.html
Apple has been supporting the gay community for a long time.
You never answered, do you choose to ignore attractions you have towards the same sex?