Jennifer Tyrrell was ejected from the scouting organisation when her sexual orientation became known.
Now, a board member at the Ohio River Valley Council has stood down.
David Sims, a lawyer, heard of Ms Tyrrell’s case last week and resigned in protest.
He told the Los Angeles Times: “I felt that it was wrong that she was removed as the Tiger Cub leader solely based on her sexual orientation.”
The Boy Scouts of America has adopted positions since 1991 which state that homosexuality is “inconsistent with the Scout Oath that a Scout be morally straight and in the Scout Law that a Scout be clean in word and deed”.
Its Scout Promise states: “On my honor I will do my best to do my duty to God and my country and to obey the Scout Law; To help other people at all times; To keep myself physically strong, mentally awake, and morally straight.”
The Scout Law states: “A Scout is trustworthy, loyal, helpful, friendly, courteous, kind, obedient, cheerful, thrifty, brave, clean, and reverent.”
Mr Sims said he was not fully aware of the policy which banned gay leaders from the private organisation.
In his resignation letter, Mr Sims wrote: “I understand that this action was taken as a result of a standing policy of the Boy Scouts of America and that said action is legal. However, Ms. Tyrrell’s removal goes against my fundamental beliefs of how we should treat our fellow human beings and is, in my opinion, wholly discriminatory.
“I understand that the Boy Scouts of America is free to run its organization as it sees fit, however, I cannot formally be a part of it based upon this policy.”
Mr Sims, who attained the top, Eagle Scout, status as a scout, urged them to reconsider.
He added that he “knew” his father, who had also reached the highest level, “would support my decision.”
The Boy Scouts of America issued a statement saying: “Scouting is composed of millions of youth members and adult volunteers, in councils across the nation, who represent diverse communities with a variety of beliefs about this issue.
“We value the freedom of everyone to express their opinion and believe to disagree does not mean to disrespect. We’d like to thank this Boy Scout Council board member for his service to youth and wish him well in his future endeavors to serve his community.”
Ms Tyrrell, 32, told the paper she was “very moved” by Mr Sims’ decision and was still hopeful the Boy Scouts of America could be persuaded to change their policy. 264,000 people have signed a Change.org petition to the same effect.