MRSA means Methicillin-resistant Staphylococcus aureus
A bacterium is a single bacteria and to be resistant there needs to be a lot more than one (we all have some on us at any time, an infection is greater than or equal to 4 micrograms/mL).
Might be a criminal or state behaviour, to chose exposure to germs as a method to hurt or kill someone.
But that as far as we know is not corporate style.
A car bomb, to deter other would-be whistleblowers, is more like the typical MO. As has happened with the original Panama Papers reporter on Malta.
B. Plenty of killings that we know of do not follow your typical MO. For example, the killing of Litvinenko by polonium which can only be created in a nuclear reactor (still the most overkill death of a whistleblower ever known).
C. In which case, is it possible you think that's the MO, because the others didn't get caught? And the corporations are now realizing a car bomb is too predictable?