You should never put a snake around your neck, IMO. Not even a ball python.

When people get bitten in the face, THAT'S usually why.

They have to grip on to hold on, they're up high and afraid which means they're just going to get more stressed and squeeze to hold. Plus if they start squeezing your neck, your blood vessels can expand and make you pass out. Not a good idea with a nice sized boa.
If you need an extended hand or something else to help, get another person or a snake hook.