Lindzei being, in my view, one of the many Gods of this planet, would probably be fairly indestructable by comparison to Orphan, who was only about as strong as a strong animal on Pulse.

The DataLogs also identify Orphan as a fal'Cie.

There were theories that Barthandelus was Lindzei according to the guide, however I find that completely contradictory and the fact that they only mention it in the guide as a passing idea and also the context it was mentioned in suggests to me that they only said that as a Pulse citizen's theory - ie, "Barthandelus is Lindzei himself!" sort of like how some people in WWII may have said "Hitler is Satan himself!".

Orphan's task within Cocoon is to give power to Eden. It is entirely possible that, when on Pulse and created by the Gods, he was tasked with giving power to locales on Pulse.