If the CEO is making the stealing part up (seems likely) the intern probably could sue Replit. Intentional copyright infringement/trade secret violations are a crime and my understanding of US law (not a lawyer) is that that makes it actionable regardless of damages.
Should he though? If he wins it seems likely he'll get nominal damages. He'll have invested a huge number of hours of his life into it. He'll be risking being on the hook for some or all of his lawyers fees depend on how the judge feels about awarding costs.
It doesn't seem likely to be worth it. Public shaming of Replit like this is a very cost effective way of punishing Replit... the legal system not so much.
This way you had to expose your own code, but it would easily win you the case in the court of public opinion. The only reason not to do this (that I can think of) is that the intern did not actually copy your code.
If the intern did steal code, the CEO only wants the project to be taken down?
Any IP agreement worth their salt would require Replit to send a formal/legal request asking the intern to destroy and return any stolen IP.
So I call bullshit on the CEO, and the intern should probably sue Replit for slander.