Islam has no basis condemning homosexuality

You didn’t really support why this the case rather compared something else that should be condemned.

In Islam homosexuality is a sin.

Yes it is

The problem comes with the fact one of Mohammed wives was a child. The Hadith that reveals Aisha’s age is Sahih al-Bukhari Hadith and for the most accepted by Muslims but sometimes it’s rejected like most Hadith.

It’s only problem for those who accepts all Hadith are 100% accurate not all Muslim believes/accept/thinks everything written in the Hadith are 100% accurate(as you mention later).

As for marrying 9 years it’s debatable in Islam if it’s consider a fact. Nonetheless their are Muslim who do defend the idea if it was true then it was acceptable during the prophets time.

However most of the Sunni Muslims think it’s authentic.

So your topic is related of Sunni Muslim who accept this Hadith. Why choose to use this to argue against homosexuality? Your topic seem to be based on non sequitur statement.

A religion where their holy and perfect prophet was having relations with a child can’t possibly condemn another form of sexuality activity.

They can and they did.

If you can provide an objective morality that applies across time and cultural then we can condemn the prophet of Islam, otherwise it’s just your subjective morals vs the moral of the past culture. It’s to be noted subjective morality it’s arbitrary and it’s very possible others might not follow/accept your version/understanding of morality.