IANAL, but as far as I understand the Idaho Code and the alibi defense notification process, I don't see how a judge can "compel" an alibi defense. The defense is given notice by the prosecutor with a deadline to respond if the defense plans to present an alibi defense (this is how it is done in Idaho, in some states it is just up to the defense to give the alibi defense notice pre-trial).
If the defense does not file an alibi response then the case moves on. The defense understands that by not filing an alibi defense, they are preculuded from calling witnesses that would testify to an alibi defense, other than the defendant himself.
I don't think a judge would "compel" an alibi defense, since it is optional, not a requirement. Maybe the prosecution is asking for another 10 days to give the defense one more opportunity to file an alibi defense? I am not sure why they would do that, but maybe the prosecution feels they need to do that since they got an ambiguous response to their first request. Then, if they get a similar response, they can move on, knowing that they tried and therefore they won't be responsible for any appeal on this issue, at least on their part.
Maybe the judge will give another extension, but IMO he won't "compel" a response, since the law does not require a response by the defense.
I do wonder if the judge will have to address some of the parameters that the prosecution set in their Motion to Compel, such as prohibiting cross-examination by the defense of the state's witnesses.
JMO.
Edited to correct that some states do not require the prosecution to give notice of the deadline for an alibi defense, but in those states no one gives notice to the defense, the defense is aware that they need to file an alibi notice pre-trial if they are going to present an alibi defense. The judge is not involved in giving notice, nor is the prosecution.
The forfeiture operates automatically, no state official will ask the defendant why he has not given notice. It is a procedural default.