I'm sure that even the Sabreliner was not intended for rolls, though, being largely based upon the Sabre Jet fighter, it was probably amply able to be rolled by a competent pilot - like maybe a former military pilot. I have no qualification to comment on rolling airliners, other than to say that none are certified for it. Aerobatics are one of those things where if you do it right, and nothing goes wrong, it may be able to be done within a normal category airplane's structural limits. But, if you get it wrong, or something goes wrong, it goes so wrong, so fast that the plane is damaged, or it's an flight break up or smoking hole. Flight test is different thing, and rarely done in front of an invited crowd of spectators.
Several accidents of non aerobatic types being flown aerobatically both for "fun" and at airshows, come to mind. What might have worked, didn't. A few attempted aerobatics in unapproved types were insurance claims, for an airplane later found to be bent. All the company pilots said "It wasn't me" - well... it was two of you!
To me, a good sales demonstration opportunity is blurred if the demonstration is including things that I'm going to be told I cannot do with the product if I buy it! Then why demonstrate it!?! It's like the pointless car ads, which show the shiny new car screaming through the desert, with a cloud of dust growing from drifted turns and full stroke suspension travel - and the words at the bottom say "Professional driver, closed course". Okay, then do you have any other cars I should consider, as I'm not a professional driver, and I'd like to drive on public roads!