People will say whatever idiotic thing comes to mind. People hear that Disney is the parent company of Marvel and they automatically think that it means that Marvel properties will now be for children only or severely toned down.
1) It shows how little people understand business politics
2) It shows how ignorant people are to corporate culture
Disney is a brand. When a company acquires another company, it is usually done to fortify existing assets (for instance, a computer manufacturer acquiring a silicon fab factory) or to expand/diversify interests (Disney buying Marvel). A company is likely to utilize an expansion purchase as a separate brand. In fact, most brands that people use, are owned by some conglomerate.
For instance, Disney owns Mirimax, and has owned them since 1993. That means that the first three Scream films were all released by a Disney company (the fourth Scream film is released by Dimension, which is part of the Weinstein company). Disney uses the Mirimax label because it is a brand that represents mature content, where as Disney is a brand that represents family content. So let people whine about Thor and Disney. They are simply ignorant people. You can either educate them, or ignore them. Do not allow such people to ruin your experience.