Is it possible Marvel intervened?
Marvel might own certain representations of Thor, but they can’t own Thor nor the historical mythologies.
Not likely. Jon Del Arroz hasn’t been informed by anyone that the intellectual property is an issue.
For example, he was personally told off by Cat Rambo at the SFWA why they wouldn’t accept a “white supremacist” Hispanic into the organization.
And he’s been informed when liberal bullies are banning him from conventions because of his politics.
Given that they tell him via social media or letter in lesser scenarios, he’d certainly find out if there was an actual legal objection.
Furthermore, the campaign is being shadow banned by GOOGLE. That means it isn’t just someone mad at him at Kickstarter. It also dovetails the shadow banning of his other works.
Liberals are just censoring conservative creators.