Hmm, that's fair. I don't use iOS much myself, so I'm not very familiar with what's available on the App Store. It does appear that at least Swift Playgrounds allows for projects (including code, which is interpreted) to be downloaded off the Internet, extending the runtime beyond what is available "at time of review".
That said, briefly looking over some scripting/IDE environments not from Apple, it looks like most of them ship "batteries included" and don't allow for content to be pulled from online.
It seems to me the equivalent of iSH shouldn't be, say, a Python interpreter/IDE, but a Python runtime including pip and the ability to pull modules from pypi.org.
OTOH, Python itself is so reflective, I imagine there's probably some way to self-inject modules within a script, if you have any sort of web access. And since you can tunnel TCP over DNS, even a hostname lookup is enough. So I'll conceded the point, since most scripting runtimes probably have some kind of EVAL routine to invoke the interpreter, or a porthole into the interpreter's bytecode.
That said, my own original point was about developers/businesses feeling uncertainty about Apple's rules, and worrying if an app would even be accepted. I feel like almost any developer would instinctively thing iSH's premise of being a program interpreter for the Linux ABI would be rejected by Apple.
Whether or not the underlying rule is fairly applied aside, it's clearly something Apple wants to prohibit. Albeit, I'm kind of baffled myself at why, especially in iSH's case where the emulated runtime is completely separate from the "real program text", with no escape hatches out IIRC. Seems utterly ridiculous to me, especially when you can accomplish something similar in WebKit/JSC I'm sure, just not offline. :-/