Why “against?” Surely Boeing is on the same team as everyone in wanting prevent any further loss of life. If they believe there is a safety issue I’m sure they would encourage the FAA to take action so airlines were obliged to.
When Boeing sells or leases the planes to the airlines there is almost certainly a clause in the agreement that represents & the warrants the plane is suitable for it's intended use: flying. An FAA declaration grounding the planes quite clearly means the planes aren't suitable to fly and Boeing will be on the hook to compensate the airlines for the costs associated with the groundings. We're talking millions of dollars a day.
They also have thousands of outstanding orders for this model plane that are, at best significantly delayed and perhaps in jeopardy.
