When I said more secure I meant it as in 6 years in the future ASICS will be mining in Thz and governments/whoever will be able to have Thz mining rigs all combined solving hashes at 1,000,000 GHz. I don't know very much about BTC but this kind of hashing power may be able to take over the network and they would control all coin activity.

If what I say is true than LTC would have a 6 year longer lifespan.

I am not really sure how hashing power effects the BTC network.