No, this isn't Microsoft simply "paying the cost of business", this is Microsoft tolerating its own employees stealing millions for themselves on the excuse that their other corrupt practices brings in business.
It's a shitty argument, I'll grant you that, but it's not a problem that Microsoft can fix. They should take the moral high ground, but the money was always going to be siphoned of.
Saying it is fine when Americans bribe in foreign countries is saying it is fine if Americans are corrupt.