This simply cannot be true. First of all, there's no mention of needing to be employed when processing your application is done. There's a condition for being in Canada when your processing is done so they could have added the employment status requirement if it was the case.You have to be employed when you apply and when you get PR, but again, we don't know anything about the processing times
Secondly, you have less control over employment status than the country you are in. You decide to travel. No one kidnaps you abroad. With employment, you can loose your job at any moment. The company could go under tomorrow. It's insane to expect people to hold any job for more than 20 days.
Please don't spread doubt based on some lawyer's guess. If they needed you to be employed when processing is done, they would have mentioned. Just like they mentioned how you must be in Canada when processing is done.
Show me one single program where the requirement is that you have a job when a decision is made on your application.