That is correct. Pulling under the persons axilla can lead to nerve or joint trauma in the area that is very slow to heal. Maybe take a look at some video on sites like

Standing from sitting | Stroke4Carers

There are also many devices to assist and simple things like raising the chair height, getting the person to look up as they stand (and not down), encouraging them to use what they have. It is very much worth the effort in forming an exercise program to work on with the individual to help them regain enough strength to affect an assisted sit to stand with minimal effort. A few weeks training to regain the basic movement patterns and rebuild sufficient strength will be life changing.