My Questions to the judges here are:
1)Does putting a token into play effect the board state?

If so, then attempting to attack without putting a token into play, in my mind, is showing that you have missed a trigger.

If not then I would like to have explained to me how so.

2) If his opponent says you may attack, then can he go back and put a goblin into play?

My ruling would be no, since he tried to attack which happens after the beginning of combat, then he has moved to a point past when that trigger should go on the stack.

Once more if there is any disagreement I am glad to hear it as it will help improve my enforcement of rules.

-Thanks-

1)It does indeed affect the board state. What exactly do you mean with “attempting to attack”? If AP just turns some creatures sideways, than immidiatly puts a tapped goblin into play I would rule this as OoOS. If he says “Attack with these” and then puts a token into play or make a pause in between I would rule that he missed the trigger.

2)Yes because of how the shortcut works. It goes to the Beginning of combat with the opponent having priority. At this time the Rabblemasters trigger can still be on the stack without influencing the game state in a visible way and there was no reason to recognise it therefore until now. If the opponent passes priority now, the token comes into play and normally the opponent gets priority again, but most players shortcut this by declaring attackers directly. If NAP had something as response to the goblin entering the battlefield he of course gets to cast his spell before declare attackers happens.

The MTR give us a definitive answer: he gets the token.

A statement such as “I'm ready for combat” or “Declare attackers?” offers to keep passing priority until an opponent has priority in the beginning of combat step. Opponents are assumed to be acting then unless they specify otherwise.

Let's dive more into the matter.

- REL
MTR apply at any event, with specifics on different RELs clearly spoken out (see Electronic Devices for a reference). That said tournament shortcuts are universal and apply at any REL as they're the basics to make games flow.

- What NAP says
Usually it doesn't matter, as AP knows how it works and acknowledge the right play even if they don't speak, but NAP needs to be explicit about it as AP has the right to leverege his superior rules knowledge to win the game.

- What they did so far
I feel there is a need to ask them if they have ever shortcut this way before. If NAP made the same play before, during this game or in a previous game in the match, and AP didn't spawn any token, then I believe they already implicitly adopted a new shortcut and I won't let him go away with an announced modification of it.

A player is not allowed to use a previously undeclared tournament shortcut, or to modify an in-use tournament shortcut without announcing the modification, in order to create ambiguity in the game.