Well, I would not void it cause both sides "agreed" for cheap playing. One team started with a bit lame hides, other side started with autofireing 4secs fulls. Comparing to a game which CF played some weeks ago.
Its very hard to respect bng as a classic scheme, with the current rules. At the beginning, teams are friendly, talking in chat about anything, trying to make nice shots etc. But after some time, esp. when some hp gone, it can suddenly change to less talk, more cheap shots / spots and so on. Just too many rules in this scheme without any live referee, which neutral decide, whats good and bad.
Change to no rules bng or just let those game count. 40 mins. or even more for nothing cant be the right way, neither a solution.