Here's a theory, and that's all it is, mere speculation. Look at google Earth to see how close the CCOC, SWFA and the Mid-Way Regional Airport are to each other. Assuming more than one perp, or a perp/accomplice, could the Altima driver have been waiting for someone to arrive at the airport and call or signal? It's a three-minute drive from SWFA Outdoors to the airport, a four-minute drive from the airport to the church.
If the perp needed to get back to the airport after the murder, (s)he might go on foot through the countryside (seems unlikely), if not, (s)he/they might leave in the Altima and go wherever they needed to hide. Are there security cameras at the airport and if so have the police checked them?
Not sure the perp(s) are criminal masterminds. They may just be lucky so far. Or maybe not. We don't know what physical evidence the police may have. However, whoever suggested that the police cleared the scene too fast because they thought it was an interrupted burglary gone wrong may be right -- although that shouldn't have excused a rushed clearance either, imo.
ETA: In case I wasn't clear, I'm speculating that the Altima driver could have been waiting for someone to arrive at the airport by private aircraft from who knows where.