It seems to me to be a challenge to God. The rainbow is God’s promise not to use another flood to destroy the Earth in reparation for man’s disobedience to His laws.
“The further we remove ourselves from God, the more we lose our identity” Saint Augustine of Hippo
Homosexuals are challenging G-d by choosing a simbow (what I call their 6 stripe sin sign) and pride, one of the 7 sins, and an abomination for their sexual preference.