Bibulus was later made governor of Syria by Augustus and he died around 32 BC. He was also possibly the same Bibulus also wrote a short biography on Brutus which Plutarch used as a source. Although that Bibulus may have been a younger half-brother by Porcia.
After being made governor of Syria by Augustus, Bibulus passed away around 32 BC.  It's also possible that the same Bibulus who wrote a biography about Brutus, which Plutarch used as a source, was also his half-brother through Porcia.