It means, in simple, that at the Federal level, it's NOT illegal for a person to record a conversation between themselves and another party.
This is also the law in the State of Arizona.
So, it's not illegal for the Pastors in question to record the private conversations they have, since the Pastor in question is a party to the conversation and gives consent to the recording.
I would argue that although legal, it is most certainly immoral and unethical.
Many states have a two-party consent law, as opposed to this one-party consent law, where both parties must be made aware. So, Apologia may be in a 1-party consent state. The phone call crossed state lines, so I don't know how this effects legality. But yes, whether illegal or not, I find this practice unethical.