I have been very much enjoying your song and the imagery contained within it, but have found my enjoyment to be interrupted by a jarring lack of attention to detail.
Of course Grandma would fail to find a button to eject - only such nonsensical vehicles such as you might find in a James Bond film would ever purport to employ such a device. Aircraft use an ejection handle, as locating a button in a cockpit, even at non emergency times, would be nigh on impossible. It would be absurd to suggest this handle could be missed, as they are very prominetly coloured to ensure the pilot has no further trouble during what is obviously a trying and stressful event.
May I respectfully suggest the following alternative lines?
'She knows how they feel as the aircraft describes an impossible angle,
She'd like to eject but the groundcrew have erroneously disarmed the ejection handle.'
Also as the song clearly does not refer to the Flankers incident at the Paris Airshow, perhaps further information as to the event being depicted would add colour to your song?
I believe that you have answered your own question.
Grandma finds "no button there" because, as you correctly state, the function is performed by a lever. However, Grandma, not being a skilled pilot (an assumption, I know, but I feel a valid one), is clearly fumbling only for a button and foolishly ignoring the lever which would conveniently extricate her from this embarrassing familial hoo-haa. The question as to why her armchair is fitted with such a lever leads to sinister answers which speak still further of the discord doing its pernicious work in this remote homestead.
I would add that it is perhaps fortunate that she was unable to locate the actuation mechanism. The likely low and unyielding ceiling of an old French mas coupled with a vertically accelerating granny would have added a grim distraction to events that might not have translated well into song.
Some valid points, but naturally if her chair were to be equipped with an ejection facility then this would be linked to a simultaneous detonation device in the ceiling above her, as is the case with the pilot she is watching fall, who have avoided breaking their necks by virtue of the explosive cord located in the canopy above them. Alternatively they would be able to jettison the entire roof. Again the song fails to make clear which is the case here, and I would invite further comment from the author.