a similar situation (kinda).
At a small tournament in bournmouth (my 3rd or 4th) I managed to get onto the final table, on the last round, with a souped up Turr and 2 bounty hunters. I did my usual 2 BH on the right side and Turr on the left, however I placed him on my board edge rather then as far forward as usual. I then did a hard 1 turn and declared a barrel roll towards me, not realizing until I Put the 1 template down that I couldn't complete it.
I was under the impression that your board edge was like another ship or obstacle in regards to barrel rolling or boosting, I was wrong.
I felt rather defeated, as you would barrel rolling 34 points off the table in your first turn.
Was my opponent correct to not allow me to take it back? yes he was, in the faq under competitive play it states that when you declare a boost or barrel roll you must complete it even if you leave the table.
Do I wish he would have allowed me to take it back? Of course. I came to the tournament to have fun games, and that pretty much ruined the last game (due to my own fault).
Would I have allowed an opponent to take it back? I hope so.
Ultimately, there is no requirement to fly causal, or play nice. The same way you arent required to say please and thank you in real life, or to give money to charity, or to hold the door open for people behind you.