I have had two horrible experiences in Liverpool Airport, where a very rude "security" man insisted I had to put my handbag into my case merely to pass his pre-security station.
As I explained, I would have to get it out in a few steps to show my check-in page at security, and get my laptop out. I told him I fully understood Ryanair's rules, but as it was impossible to get through the security check with "everything in one bag" it was pointless of him to insist I did it at his position.
I demanded an apology for his behaviour from the airport management, but had a very off-hand letter in return. I stated I would not only NOT travel through Liverpool Airport again, but would publicise their customer-unfriendly position.
I was so flustered after the unpleasant encounter I actually did get on the Ryanair flight with my handbag still on my shoulder, and nothing was said by the Ryanair staff.
So, you may not have to observe this rule, but should be prepared to fit the handbag into the case if required.