Removing the airbox can if you are not aware end up in breaking the rubber mounting bush ( repairs 100% with superglue)
The correct way is to use a 22mm spanner under the airbox bracket to hold the top of the bush .
However once you have it off you can fit a simple bent bit of metal to hold the top to save using the spanner.
Diagram below ..just leave it in place under the bracket and the jobs easy next time.
The bent down bit holds the nut in place .