Well, according to our FOM, a mechanic is approved to ride in the cockpit
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An on-duty FedEx Express mechanic en route to or from repairing aircraft in the field.

So, totally okay and approved by the FAA for "Bob" to ride with a view one day, but let him try and ride the Jumpseat (P) to visit his dying Grandma the next and all heck breaks out

And who didn't love his Grandma, all those cookies she used to bake. And who didn't cry when she taught Bob to read?