Well that's dumb. Why did Shu alter his own memories? Why did he alter Lava's memories? She already thought she was the one who did it. He could have just given himself up and explained what happened, or even better used his powers on the responding police to make them think they all watched Chris release Lava and run away.
Well yeah, he's a moron. He could testify in her favor exposing the whole thing. Chris was even arrested not long after that anyway.
At least Shu is written pretty consistently incompetent at his job and making the worst decisions by himself.
I can see him altering Lava's memories as way to take away her guilt on that. It's the thing that he could do since he relied on his powers so much. It's really selfish and far from being a good decision but he was desperate at the time.
But I don't think he could alter the memories of the police or everyone around. He relies on touch to use his powers so he's not that overpowered like Xavier or Jean Grey.
Instead, he erased his memories of the evil organization he just betrayed which would mean if they came after him he would not expect it. Chris could just come back for Lava and they would be completely taken by surprise. What a moron.
Well, that just happened...
So he knew she was innocent this entire time, yet he let her be put in jail for life instead of sharing that information, even when Chris was later caught and imprisoned. This is nonsense.
He later altered his own memories to match what he did to Lava.