Rose tweeted that Cook is "the Donald Trump of the music industry." That's likely not a compliment for iTunes-owner Apple.
Rose has been a vocal critic of the president and his deputies Ivanka Trump, Jeff Sessions and Vice President Mike Pence. (During Trump's campaign the rock band had a pinata of Trump at a concert, according to Billboard, and guitarist Duff McKagan has been known to write political commentary.)
Cook himself has not been supportive of all of Trump's policies — Cook openly condemned Trump's decisions to withdraw from the Paris climate agreement and to tighten immigration from Muslim-majority countries.
But Apple has been a big beneficiary of U.S. tax reform, championed by the Trump administration. It's not clear if there's a connection, but Rose would not be the first to point out a connection between Apple's wealth and its efforts (or lack thereof) to pay musicians. Kanye West also addressed Cook a few years back, saying, "Hey, Tim Cook, the Head of Apple, stop trying to get performers to play your festivals for free. You are rich."
Still, Apple's proponents often point out that iTunes tamped down illegal music filesharing and provided artists a way to better monetize online music. Cook has said supporting musicians is more important to Apple than money.
Apple did not immediately respond to a request for comment. Axl Rose could not immediately be reached for comment.