FDA’s top tobacco scientist takes job at Marlboro-maker Philip Morris

Is that stuff news? It's well known that FDA guys do favors for the industry and then go work in executive positions a few years later. Legal kickback for useful "friendships".

You should be also aware that the FDA hires external consultants to do some of their review/expert work, and the same consultants on the other hand are paid by the industry to write filings (for new drug submissions and more) that end up at the FDA for review. Complete conflict of interest in the open, and nobody does anything about it.

Public servants should be banned from getting a job at a related private company for a period of at least 5 years. Otherwise the public servant isn’t serving the public, but the corporations.

Why would five years make a difference?

It would raise the effective price of switching, making the bribe more expensive.

Where else would a tobacco scientist work but at a tobacco company or in the government?

The problem is not the move, but the fact that there is a cozy relationship between the authorities that regulate everything, and the industry that makes stuff. You can't trust either party if they collude.

Where it’s not a conflict of interest.