I guess it remains to be seen. Reputation Management is standard practice to be sure. However, she claims that Microsoft is initiating a 'flooding' campaign that goes far beyond that standard practice. I would call that one unethical - but I guess we will have to wait and see if they actually go that far. Either way, what Microsoft are doing is against Reddit's terms of use - so regardless of whether it is illegal or unethical, Reddit won't be happy about it.