I am often moving about with 2 children with SNs - not toddlers, but pre-teen. Even at that age, it's hand holding and shepherding them where I need them to go with respect to the bus, tube, train, walking. Because they're a bit older, we have really drilled them on "pardon me/excuse me" or "sorry" if they bump into people, and either making room or staying to a straight path so it's easier for people to get around us with as little incident as possible. I am, however, having an ongoing conversation with them as we're walking, so anyone with ears can likely tell exactly which direction we're going as they hear me say "okay, we're going to turn right at this corner, get ready to turn right....Okay, right... right..... good job!" 
My most used expression is probably "stand on the right, stand on the right" as we approach and go up/down the escalators at the tube stations, although they're getting much more reliable about it now, they still get a reminder.
Most people are quite patient about it, but then if someone is coming up quickly behind us, I tend to try to allow them room to get by as we simply do not move that quickly due to their SNs/disabilities.
The screaming can be an issue - if they launch into meltdown, it's sometimes unsafe to move them until they reach a point where... well, where it's safe to move them. I certainly don't want to drag them kicking and screaming past a couple small children or breakables, where there's a chance someone could get hurt or something might get broken. And as pre-teens, I can hardly just pick them up and carry them out (safely for myself, them, or anyone else). So if that becomes an issue, I try to shut it down as quickly as possible. But if someone actually thought I wasn't trying to fix the situation, they would clearly not be paying attention, as it's always very clear that I'm trying to sort it as quickly as possible.