1) Is the 60-day notice of effectiveness automatic in this case? Wouldn't regulators have something to say about a form 15 filer committing malfeasance and then turning around and registering securities?
Yes, the registration statement would become automatically effective in 60 days. No, the SEC wouldn't make a point of expressing displeasure. Maybe the reviewer would ask why it did that, but I really don't know. It does happen, and not necessarily for sinister reasons. In most cases, it's because the company has received a financing offer that's contingent on it being an SEC registrant current with its filings.
2) Assuming the notice of effectiveness goes through and the shares are registered, what is the likelihood that a form 15 filer could return to full compliance?
I doubt there're any statistics on that, but it's what they're obliged to do.