I think we have to wonder why the change in thinking.
Immediately after the deaths.
"I didn't hide the bodies. I placed them there. I expected them to be found," the accused man replied. Link
After Lynn realised that HE was on the police radar.
"I realised it was unravelling," Lynn said.
"I realised I had to go back ...
Lynn told police in November 2020 he returned to the Union Spur track where he set fire to the remains of Hill and Clay. Link
It is reasonably certain that something about those remains pointed to murder.
Because Lynn destroyed the remains, then later showed the police where the place of destruction was.
imo