Not true. He’s saying “big league”. You relax.
I don’t care if “bigly” is in the dictionary. There are plenty of improper words in in the dictionairy these days, including the abomination known as “Ebonics”.
You go right ahead and say “bigly” if you want to come off as being inarticulate, and while you’re at it, say “axe” when you mean “ask”. Say “nucular” when you mean “nuclear”. Say “mute” when you mean “moot”. Say “irregardless” too, if you want to sound like a moron.
Bigly is actually a well documented adverb. “In a big manner.” Donald Trump has won bigly.
He is saying “bigly”. LOL. You are the only person in the world who claims otherwise. Bigly is said loud and clear. He is not mumbling big league. LOL.