Here are some ways that Healing might be able to defeat a xenomorph.

I've now watched a couple of the Alien movies, and taken mental note of a few things as I've watched (because I'm insane), which gave me the idea for the first Halloween post of this year.

Without further ado:

A Healer wouldn't be in much danger at all if attacked by a facehugger; a Healer's magically altered immune system can detect malice or intent to harm, and release a calming chemical in response. The chestburster wouldn't be able to gather the strength to claw its way out as usual, and would be contained.

If someone else got attacked by the facehugger, they could be taken in and protected by the Healer.

Healers cannot be harmed by acid. If necessary, a Healer could take on a xenomorph hand-to-hand without the risk of being burned by its blood (though the taste of it would still make them sick).