Language is malleable, and so while it may be paranoid to question a feature labelled as zoom now, it's an open question how long that will last.
That's not how technical claims of that nature are normally handled.
The fantastical claim was from the defence. Onus should be on them to prove it, rather than making the prosecution prove a negative.
It's also likely that precedent testimony exists on using an iPad to zoom into an image or video in other cases.
And both the prosecutions and defense's claims were fantastical, unsubstantiated (beyond some incorrect 'common sense' handwaving) and wrong - so since it's the prosecution that wants to enter new evidence, it's perfectly fine to ask them to back to it up. This isn't 'proving a negative', it's just asking them to prove that what they said (that zooming doesn't change the evidence).
Both prosecutors and defence attorneys have used the same mechanism countless times in previous cases, without issue, because it is actually common sense that pinch to zoom is not going to substantively change what's shown in a video like that.
In this case the prosecution wanted to significantly zoom into very grainy footage to ask about an object a few pixels wide, on footage so grainy the prosecution couldn't identify the face of their own lead witness.
The defense raised the question regarding zooning altering or adding pixels and the judge said flatly he didn't know. All the prosecution had to do was bring in an expert on video to explain how zoom works - or have the expert do a non-fractional proportional zoom.
Everything is common sence untill it isn't.
Its common sence that you can't take over control of a car over the internet and kill everyone in it, that acess to a website that shows realtime location of half of US polulation would at least be properly protected, that a car's accelerator pedal doesn't cause random and unpredictable effect thanks to spagghetti code, that when Fujistsu charges a postman for theft, they are not just covering up bug in their tracking and accounting software.
Which is why both sides can ask the other side to substantiate their claims or provide expert testimony to justify their claims. If there is no issue, then the other side will be able to relatively easily find someone to testify to that or provide other evidence.
It's how the system is meant to work. If this is being used abusively, the judge will catch on soon enough.
That's because criminal law is purposefully biased in favor of the defense. If the prosecution wants to argue that they defendant appears to be pointing his gun at somebody when they zoom in on a photo with an ipad then they need to prove that the ipad's software can be trusted to do so reliably. If there are programs that can upscale images by creating new data then they need to prove that the photo app on their ipad is not one of those programs.
This should have been done with a program that is open to scrutiny (and ideally one that's open-source) so that the algorithm used to upscale the image is known. It's not enough to just assume that the ipad uses bilinear interpolation when there's a reasonable doubt that it could be using another algorithm.