Not long ago I traveled on a rush hour South-Eastern train from Victoria Station to East Croydon station and one man had a full size bike across a door and gangway area among all of us standing, adjusting it's position each time someone needed to pass. I didn't see anyone show the slightest annoyance, indeed most were helpful in allowing for the bike's movements.I'm just put off by the weight of the bike and the thoughts of carrying any bike at all during rush hour on a train since it must be very annoying for other passengers!
On that basis I'd be surprised if a politely handled folder would cause annoyance.