How do we know that LE didn't search the lake well??? Weren't they there multiple days?? One or two pictures of them searching doesn't mean it was one diver and/or one boat and only one area. I think they spent days searching the lake and to no avail. They were convinced he wasn't in the lake. The dogs followed his scent out of the park.
It was hot, it wouldn't have taken too long for a body to decompose in the lake and rise to the top. It's a manmade lake, sure there might be debris in the bottom, but it also means it's not near as much as a natural lake would have, being there over millions of years.
I know sometimes the dogs are wrong. In Dylan Redwine's case, dogs alerted several places around Lake Vallecito and he was nowhere nearn there, his remains were found miles away up in the mountains. And I know not all bodies float to the top, some do get caught in sticks and twigs and falling trees, but once again, Lake Castaic is a manmade lake, how many fallen trees are in it?
I also know sometimes (well many) that LE is wrong, once they've cleared an area, only for someone to find the body later. However, many times they've been right, when there was no indication someone was in the water, and the dogs supported that indication that they had left the immediate area.
I think there is still all kinds of other things that could have happened to him. As long as a body isn't found, there is hope. IMO, JMO, MOO.