Also, treat email conversations as “unrecorded” if they’re using your university email address. Make sure to download a copy of all email correspondence to a storage device outside the control of the university.

This is really important, they can delete emails. And if they do, that's one more point for your case.

It seems reasonable to at least attempt to resolve the situation by emailing someone higher up than whichever random bureaucrat put a hold on his account before immediately jumping to hiring lawyers.

The lawyer emails someone higher up, otherwise the higher up will simply smash the hammer harder to protect against liability. Showing up without representation here is a mark of unseriousness.

Adult businesspeople always have lawyers do the fighting for them; if you don’t it says more about you than the fight.

Not necessarily. The more damage you do to someone, the higher the potential liability. Smart business people usually know that de-escalating is often the best choice.

That’s just not true dude. Most professional adults try to resolve things amicably before immediately getting lawyers involved.

Lawyers are how professional adults resolve things amicably. Having your lawyer handle it doesn't mean the interaction isn't amiable, it means that the person amicably resolving the situation is both aware of their legal rights and responsibilities, and that the principal is savvy to the concept of liability because they have a professional advising them.

Almost all things resolved via lawyers are resolved professionally without a trial or a fight. This is literally the primary function of lawyers: to interface with the other party's lawyers and find a mutually consensual resolution to a problem without compromising your own rights and entitlements.

Showing up without a professional sends a clear signal to the other party that you're not interested in doing the minimum to protect your rights and ensure that the other party doesn't steamroller you, which incentivizes the other party to trample your rights and steamroller you, because there's a likelihood that you haven't been advised of your rights in full and don't have an immediate and convenient path to enforcing your rights against the counterparty. It's bush league.

Get a lawyer. Have the lawyer handle it. "Handle it" doesn't mean an immediate lawsuit, it's simply the way professional organizations indicate to other professional organizations that actions have consequences. No lawyer means you don't intend to cause them any consequences, which means you're ignore-able.