No way is he stronger than 3 eyed Madara. Hagoromo doesn't even have the third eye. Madara's CT could be way bigger than Hagoromo's moon sized one. He'd put up a fight, but it bothers me that people think that this is false.
Ashura and Indra came from Hagoromo, and it has not been enstablished that Hagoromo gave
all his powers to both of them, ergo:
Hagoromo >= Ashura + Indra
Madara is only a mix of both Ashura and Indra's powers.
Madara == Ashura + Indra
So, under Boole's logic, we could infere with ease that
Hagoromo >= Madara
The only reason that lend people think that the current Hagoromo could not defeat Madara is only because he lacks the chakra to do so. But the fact that Hagoromo is dried up is as good as Madara being dead right now, so... I guess you're up to prove me wrong.