I haven't commented on the pour date up to now, but I do think it's highly relevant, regardless of whether or not anything was found.
Here's why it matters vis-a-vis SM's disappearance:
If the concrete pour at that site occurred prior to Mother's Day, then clearly, LE does not have proof of SM being alive and well on Sunday, May 1oth.
If LE had proof that SM was in fact alive on MD, and the pour happened prior to MD, then obviously, SM could not be underneath that concrete.
LE would have zero interest in looking under that concrete if they had any proof of SM being alive AFTER it was poured, and even if for some completely irrational reason they did, no judge would sign off on a search warrant asking to look for evidence r/t her disappearance if there was evidence of her being alive AFTER the pour.
If that pour happened on 05/09, then LE does not have proof positive that SM was alive and well on 05/09.
Ditto 05/08.
Pour date matters, because it tells us a lot about LE's timeline development.
JMO.