He really was stupid.
But think about it. If the plane was not delayed, he would have had several hours extra. Girls already dead. Wife could be gone as soon as she got home. CW would have had double the time to get all of them into an oil tank. Hiding place was excellent. Almost impossible to trace, as long as he moved the bodies carefully.
Get back home, clean up, text his wife, and go to work.
Probably would have been helpful if he had not been so overconfident about his “acting” skills. Since he didn’t have them. Probably got inspired by other recent disappearance cases and figured that if all the bodies were safely encased in oil, he’d be okay—no bodies, no crime.
But he didn’t have a Plan B. So when Plan A screwed up, he screwed up. And then he made it worse by acting totally stupid in front of the media and the police.
Which, good. I’m glad he didn’t get away with it. But I do think that in his mind, the planning was airtight, provided everything fell into place. Which it did not.