If you play Brynhir Thundersong in response to Cull the Weak using Here to Help, does Cull the Weak still resolve or does it get countered?

Ruling: Cull the Weak still resolves. Brynhir Thundersong only prevents new things from being played or added to the chain after it resolves, but does not counter cards already on the chain.

Sequence:

• Opponent plays Cull the Weak
• You react with Here to Help to play Brynhir Thundersong
• Brynhir resolves, preventing new cards from being played
• Cull the Weak still resolves normally