You do realise that almost all cars until recent history had completely open undersides and got covered in all sorts of road muck routinely? 5 minutes ago this was normal and people were not worrying about ill effects.
There was a time before the policy was set which is probably when this someone had it fixed. MG can introduce a new policy whenever they like.
There's nothing unhealthy about it according to MG.
But go ahead, and good luck and yes I think you are making an unwarranted fuss but that's ok for us to disagree. People think I make unwarranted fusses about all sorts of things!