Oh, boy. Author has a very weak understanding of the period.
For one thing, Pompey’s campaign against the pirates could not have been facilitated by his conquest of Mithridates, since it preceded that conquest. His being given command in the war against Mithridates was a result of the pirate campaign, not the other way around.
For another, the Republic’s institutions were already in tatters at this time, with a major civil war, including the conquest of Rome by its own armies, and the installation of Sulla as a military dictator with absolute power something like 10 years earlier. Sulla used his dictatorship to completely remodel the constitution and to proscribe and excecute his enemies without trial.
Sulla’s dictatorship was a MUCH more consequential episode in Roman history than the Lex Gabinia. It demonstrated beyond any doubt that real power was wielded by the warlords, not the Senate or the People.
Also, while I guess it’s a bit of a nit, the Senate did not pass laws. Those were passed by a variety of Assemblies of the People.