Received coins in offline Armory wallet that had not yet been synced
Is the delivery address valid even though armory was never connected to the internet ?


Yes. There is no need for a wallet to be online to receive Bitcoin.


  can i access the funds at a later time with the private key that was generated by armory ?


Yes. Once Armory and Core are fully synced, you can access the funds. Alternatively you can export your private keys and import/sweep them into another wallet and access your funds from there.