Seems like neither of those people can really confirm the sex therefore I would suggest to find someone that can sex your animal accurately.
Yes two males can lock, been there done that.
Problem with popping pictures is not knowing if you put enough pressure or not no real conclusion can be made, if the wrong pressure was applied and the fingers were not properly placed than you still have no certainty.
Remember larger individual can be much harder to pop and if you are not proficient at it you might make the wrong conclusion.
Looking at the pic I say male but you are not able to pop him successfully. (not enough pressure)