LE may have never officially commented on TG's bike sighting, however, LE were fully aware of it, since it was reported through MSM and TG himself talked to LE at the lake that he may have seen the bikes.
IMO, if LE wants the public's assistance in solving this crime, any information that they become aware of that is factual, whether they officially initially reported it or not, IMO is their responsibility to report to the public what they know to be true.
Since LE want every tid bit of information, no matter how insignificant the person reporting it may think it is, the information regarding the possible sighting of the girl's bikes by TG may have been very significant to someone out there, whom may have had other relevant information surrounding this piece of information.
We are just finding out now, two months later, that LE knew this was not L's and E's bikes.
IMO, it is LE's duty to report what they know, if it can assist with solving this case.
But JMOO.