The whole thing is just for show, I don't believe they expect to win this, it's a message to anyone who wants to try on the future "we will try to destroy your life if you resist even slightly"

They are claiming he destroyed evidence.

Evidence of what? What crime did he commit that you are searching the phone for evidence? If you don't believe a crime occurred, not only do you not have a reason to search the phone, but it doesn't matter if he took out a hammer and smashed it to little bits, it's his own property and he's free to do with it what he likes. He wanted to wipe it, and he got it wiped. What you wanted in that moment didn't matter in the slightest since you have no probable cause to search, no crime committed, no reason to baselessly charge someone for destroying something that doesn't exist.

It sounds exactly as ridiculous as someone being charge only with resisting arrest. If the person had provably done a crime worth arresting, that charge would be there as well.