Plot hole?
How was Soichiro able to see Light's lifespan, if Light is still in possession of Misa's notebook? It seems like even the rule would apply to "borrowed ownership" as well.
shareLate reply, but only the owner of the Death Note has their lifespan invisible to people with Shinigami Eyes. Misa was still the owner, but Light kept it on his body to retain his memories.
By the way, this is the live action board, not the anime one.