For further clarity that the issue was ultimately resolved by EA, not random chance, here's the email I received about an hour later. Again, to be clear, the quest being mentioned below is "Rake it to the Limit". The "Flaw and Order" questline was completely bypassed.
Hello!
Thank you for contacting EA Help for assistance. My name is Zeanne and I am the advisor that has worked on your case today. It's frustrating that you are experiencing this issue for your Simpsons Tapped Out game. I see that you were having trouble getting that slippery Sideshow Bob to show up in your game. Fear not! Our wonderful expert, Leslie, has captured that fiend and added him to your Springfield.
He should now show up in your town as Bob Terwilliger and have an ! over his head for his quest that is waiting to be done.
If for some reason he doesn't show up for you, please log completely out of your account and let us know that he isn't showing up for you. We will get this back up to Leslie for her to fix again. Please note, if we need to do this, she has asked that you not log in again until she fixes it and lets us know it has been done.
Hopefully, all will be well with your town and you will be able to get Bob Terwilliger questing along with your other characters. Leslie has also added 50 donuts to your account as a small compensation for this taking so long to get fixed for your account. You should see those as soon as you log in again. I would recommend that you make sure your Donut Confirm Spend tool is switched on to keep Homer from going after those fresh donuts.
I hope this helps you out. Thank you for contacting EA Help with your game issue. It's been a pleasure working on your case today. I look forward to your response. I have set this case to 'Waiting' in case you need to contact us again about this issue.
This case will automatically close at the end of 7 days if no action is taken before then. After that, if you still require assistance you can contact us through Help.EA.com and set up a new case and we will be happy to assist you. Please go to help.ea.com to check on your case status.