Any way they can get that piece of paper is fine. He says what they did was plainly wrong, but he has some sympathy for their circumstances. They knew what the results were supposed to look like, but it wasn' t working out. They only had one crack at it because we didn't have the manpower to keep the lab open an extra day. And many of these students were set to graduate in a month.
Every case is unique.
You can't just have a knee-jerk reaction. But we know professors don't always do it. Some want to deal with it by themselves and talk to the student privately. Some professors fear that the sanctions the student will receive will be too severe. But the strictest punishments, including suspension or expulsion, aren't often handed out.