I think we need to go a step further: an LLM should always be treated as a potential adversary in its own right and sandboxed accordingly. It's even worse than a library of deterministic code pulled from a registry (which are already dangerous), it's a non-deterministic statistical machine trained on the contents of the entire internet whose behavior even its creators have been unable to fully explain and predict. See Claude 4 and its drive to report unethical behavior.
In your trifecta, exposure to malicious instructions should be treated as a given for any model of any kind just by virtue of the unknown training data, which leaves only one relevant question: can a malicious actor screw you over given the tools you've provided this model?
Access to private data and ability to exfiltrate is definitely a lethal combination, but so his ability to execute untrusted code, among other things. From a security perspective agentic AI turns each of our machines into a Codepen instance, with all the security concerns that entails.