It's not beyond the wit of invention that someone might decide to go to the toilet and "see/smell" smoke in there, and as the exits are next to the toilets just pull the handle on the door.
Yes, well that would certainly mean nobody was going anywhere that day. Except the offender of course, who would very likely become a participant in the criminal justice process.
It is worth bearing in mind that less worldly sections of the press (and public) do have a habit of reporting any piece of tarmac hardstanding that an aircraft might be using, as "the runway."
Whatever the delay, it is most unlikely that an aircraft would be allowed to volunteraly block a runway for any length of time.
The decision to board the plane and what to do subsequently rests with the Captain. However the Captain is constrained by the realities of the situation he finds himself in. Obviously any delay, but particularly a protracted one becomes very frustrating for the passengers and that would be a point not lost on an experienced crew.
With any delay, the best position to be in, is to be ready to depart as soon as the opportunity arises. This means having everybody on board, with all holds and doors closed, a tug attached (where required) and the ability to realistically be airborne within 15 minutes. In situations where a slot becomes available, or you put yourself in the "queue" when a restriction lifts, you simply will not be entertained unless you are "ready" as described. Obviously this cannot be done if you need 40 minutes to re-board passengers.
From a Commanders viewpoint, it is a simple decision when the delay is defined. For example an airport that is declared closed until a specific time, allows for re-planning. However rarely is this the case. The crew will be repeatedly asking for updates on the delay, and usually there will be no available new information, or simply a vague indication. All the time the FTL (Flight Time Limitation) clock will be ticking, and the crew will have to consider that at some point the flight will not be able to depart as planned simply by virtue of that.
All in all, it is a complicated juggling act. Safety is obviously paramount, but there are many operational considerations that are not always obvious or sometimes understood by the passengers. Good communication should hopefully aid on that front, but so often there is such a scarcity of hard valid information, that it is difficult to address all of the frustrations. Passengers have entered into a contract of carriage, and the captain will, subject to all the usual provisions, want to ensure that contract is fulfilled.
Ultimately the length of time the passengers should be held on board cannot exceed the length of time the crew could be on board and still perform the mission. Of course that may well involve a lengthy delay.
Another point to bear in mind is that stands, once vacated, may not be available to a returning aircraft. Steps, transport and other ground equipment may also be in short supply.