RAW it does not block Aura of Life:The purple worm can swallow the barbarian, and that will block Aura of Life's line of effect. Unless the worm swallows the cleric too before the barbarian dies.
"Life-preserving energy radiates from you in an aura with a 30-foot radius. Until the spell ends, the aura moves with you, centered on you. Each non-hostile creature in the aura (including you) has resistance to necrotic damage, and its hit point maximum can’t be reduced. In addition, a non-hostile, living creature regains 1 hit point when it starts its turn in the aura with 0 hit points."
Nothing in there says it is blocked by cover or requires sight. It is actually better if the Barbarian gets swallowed. Since he is 3rd level, if he is not swallowed there is a minute chance he could actually be killed with a really lucky crit. If he is swallowed he goes to 0 every turn and is back up to swing (with disadvantage) next turn. With 100 turns to kill the purple worm, he will eventually get there.
The point is this - this spell is WAY, WAY, WAY more powerful than twilight sanctuary when it comes to keeping allies from being killed. It is not even close and keep in mind we are talking about a ridiculous case here, a single 3rd level character. Put that on a 7th level Party (still generally woefully overmatched) and you will beat that purple worm almost always. He needs to be extremely lucky to win a fight. Do the same with twilight sanctuary and it will be a TPK. And I have never seen anyone suggest that aura of life is OP.
While I am at it, I will note a lot of players will do better inside a purple worm then outside of it (assuming they survive the bite) due to spells like protection from energy and absorb elements.