Sen. Marco Rubio (R-Fla.) said Sunday serious questions are rising about “McKinsey’s core values and corporate culture” by the famous international management consulting firm’s order barring its Moscow office employees from joining the growing protests in Russia against the arrest of Alexei Navalny. Navalny was arrested last week as he returned to Russia from Berlin where he was recovering from his poisoning five months ago by a military-grade nerve agent known as Novichok. Navalny is one of Russia’s most prominent critics of Russian President Vladimir Putin. His Jan. 17 arrest sparked demonstrations Saturday that the Associated Press said saw more than 3,000 people arrested by Russian police. In an unusual statement issued early Sunday, Rubio made public a letter in which he blasted McKinsey & Company Global Managing Partner Kevin Sneader after Sneader’s firm told its Moscow office employees they were forbidden from participating in “illegal” demonstrations. The firm subsequently …