they fought after Big U managed him.. Big U isnt some A&R, or anyone in the music business.. he extorts people..There wasn't any beef. He acted up like a kid and the OG put him back in his place.
Big U was the one who brought Steve Lobel in. Steve Lobel does not manage Nipsey Hussle if Big U doesn't say 'This guy is better than I am' If he was bitter and jealous why would he bring in a guy who would make Nipsey a bigger artist (which is exactly what happened)
therefore, he couldnt give the "ok" for Nip to sign with anyone.. especially considering, Nip was never signed to Big U..