My only reason for posting was to save folks from possible grief. It's certainly a matter of opinion and personal preference on use of petroleum jelly. As a former owner I seriously admire Porsche engineering but please note, their advisory addresses alloy wheel and body weatherstrip maintenance, not o-rings.
I won't trot out my resume here but I spent a lifetime with a huge variety of equipment that depended on o-rings. If an o-ring is made of or contains any petroleum-based compound then petroleum jelly may cause that o-ring to break down, actually melting it. It may take a while to realize it happened. When an airgun is shot whatever is used for assembly lubricant will be distributed throughout the gun eventually. Several but not all plastics are damaged by petroleum jelly so if the 'wrong ones' are anywhere in the gun that may cause problems over time.
A particular mfgr. of a product may suggest using petroleum jelly on their o-rings, because they know what their o-rings are formulated from and have done their research. That's not to say then that all o-rings can tolerate petroleum jelly. Other o-ring formulations may not be compatible with it and might require a specialized lubricant, maybe silicone based. However silicone based lubricants will attack silicone o-rings. Some info at the link: