That's what the LA Times leads you to believe but it's not exactly true.
Gavin Newsom opened a fundraising account to run for governor in 2018. Every candidate who thinks they may run statewide some day opens up a statewide campaign account. Kevin McCarthy, the House Majority Leader, had a campaign filing or Lieutenant Governor last cycle. I don't think he ever considered running, but candidates need to file an intention to run for statewide office in order to raise money. They can maintain that account pretty much forever and can switch the race to any statewide office. Newsom wants to raise money he can use in the future and he is termed out of his current job. So he had to pick something. He picked governor. Which he'll probably run for in 2018.