The key is that everyone is comfortable with the situation and gets the rest they need. You must get a lot done. She was learning what her baby needed and decided to do whatever she had to to comfort and calm Elizabeth. She adamantly stated that no one else spent 24 hours a day with her child, so how dare they make judgments on how she was parenting her baby. Parents are then encouraged to do whatever comforts their baby best.
Some babies nap best in mother's arms.
Some prefer a sling. Kevin napped in my arms when he was a newborn, then transition to a swing. But I've always nursed him to sleep before transitioning him to his nap-spot. There is no right way for your baby to nap. As long as she is getting the daytime sleep she needs for good health, however that occurs is what works for you.