As a general rule, I let my residents do what they feel is best for them. If it's not hurting them or anyone else (including me) I let them have their head. However, I've had several situations where the choice has been causing them pain or getting hurt myself. I'm sorry to say I had to choose causing them pain.
The goal is to let the resident do as much as they can themselves. This means getting up from their chairs with just enough help to keep them safe. I'm willing to do it in several small, slow steps and to ease them down gently into their new space, whether this is the bed, the toilet or wherever else they want to plant their fannies. But when they stop midway between the Scylla and Charybdis, I'm going to move them as quickly as possible.
I had to muscle a resident last night because they did just that. They stopped and I was stuck between them, the bed and the recliner. Either they were going to fall or I was going to get hurt trying to hold them up. So, I got them seated on the bed and rolled over onto their side (which is how they like to sleep) while listening to them scream. Ugh. If you've ever had to do that, you know it makes you angry. At them and at yourself. After I got them settled, I apologized and explained why I had done it, but I know it didn't comfort them much. And my voice was sharper than normal, I know. My only comfort is that they likely forgot it as soon as the pain subsided. They were sleeping quietly when I left, so I believe all was well.
I accept the fact that I'm going to be sore after work. But if I get seriously hurt, who will care for them? Given the choice between hurting them or hurting me, it's going to be them. And it's a crappy choice to have to make.