How does a person learn good aikido without a good lineage? I doubt the dude is O-sensei and can make the stuff up. Possible, but not likely.
In the end you can't be lazy about being a student and say that good aikido is defined by good lineage. The teachers I trained with the longest and admired most, I never knew and never asked who their teachers were. It simply did not matter. They were awesome, and their abilities spoke for themselves. I have also seen bad aikido under the banner of verifiable and impressive lineages. Evaluate what it is you want out of aikido and then go see if this teacher has it.