Yes the rinds or skin of the spaghetti or spaghetti squash is edible and you can safely eat it.
The rind of squash and spaghetti squash has many nutrients that are good for your health so if you want to eat the skin or spaghetti squash skin or rind you can safely do so and you'll improve your health.
I always eat the skin of any squash including spaghetti squash because I love the skin as well.
Sometimes I'll peel the skin off the spaghetti squash or other squash and then deep fry the spaghetti squash or other squash skin.
So then I have deep fried spaghetti squash or deep fried squash skins which are delicious.
There's no need to throw out the rind or skin of the spaghetti squash or other squash as it's perfectly edible and very safe to eat and health for you as well.
When you throw out the rind or skin of the squash you're throwing out good nutrients that are essential for your health.