There is more traffic that one would think. The intersection of Bonnett and Vacation Club is a big kiss and drop area for local runners. In addition, many cast members will be whipping up Bonnett to avoid the huge traffic on World.
It is not advised from a safety perspective.
If you choose to do so, remember that most Orlando mornings are like a spring/summer morning in the rest of the country. The grass is wet from dew and from sprinklers. You may end up with wet shoes before the gun even goes off.
In the event you do choose to walk from PO understand that you will be entering the start area from the incorrect direction. I have read reports of years when security blocked that entrance path. Understand that you must cross an easily patrolled crossing of a canal that is two lanes wide. If they opt to control the intersection the year you decide to walk you may be shut out. If not expect to be challenged at least 2 times if not 3-4 times for a bib. Make sure you can show the bib easily.
You will not be able to drop a bag if you walk as the bag drop is a good .6 miles upstream of where the start is. The benefit of walking would be to wait to close to the start. So you will be without any post race stuff. Then you will be riding a bus back to the resort post race any way.
The bus service works well. Driving works well. Why take a risk of injury/wet shoes for the short cut.