You don't need to read minds to know that abusing your dominant market position in one market to disadvantage your competitors in a different market (advertising) has a very high likelihood of breaking competition rules. That's a textbook example of anti-competitive behavior.

When did they change their minds, can you provide a link to a previous regulatory decision which approved this behavior?

So, like being a citizen then?

All laws are inherently vague. Some actions are clearly legal and some are clearly illegal. Between them, there is a gray zone, where it can be impossible to say in advance what's legal and what isn't.

If you are an amoral profit maximizer, like the average publicly traded company, it's often rational to take risks by entering the gray zone. Sometimes nobody cares that you do that. Sometimes you manage to get a favorable court ruling. And sometimes the expected gains outweigh the eventual fines.

It's almost always easy to comply with the laws by playing it safe. But shareholders don't like that.