We have no idea whether the signal had a pattern because the only recording we have of it consists of averages over 10-second samples, so any modulation <10s (or patterns larger than the 72s recording) would have been lost. It could have been an AM broadcast of a herd of circus elephants playing the William Tell Overture for all we know.

Yep. It's wildly unlikely that this was any kind of deliberate signal. Whatever caused it, it only happened once -- which isn't what you'd expect from aliens hoping to make contact.

We only recorded the fact of the signal's existence, without enough resolution to make out any pattern within it. If the aliens were hoping we'd decode it, they were banking on us happening to catch their signal at a very specific instant in time, never to be repeated.

On our timescale, sure. But then we wouldn't want to communicate with intelligences that experience time so differently that a pulsed signal from their perspective would be a single pulse from our perspective.