I think how bad of an idea this is has been covered but one other point needs to be made - you need to dump that marketing guy as his thinking is so far wrong as to be borderline criminal. God knows what if he decides your website should start doing something similar on a drive by basis? Wrong headed as can be and you really should not associate with him further.
Dump someone because of a creative idea? Wouldn't be many "mad men" in the world if agencies worked with that rule of thumb.