The lawyer can make any case the client wish, but not by knowingly lying to the court (note that not sharing privileged information is a very different thing). In other words, saying things like "my client's position is X" rather than making false statements of fact. And not falsely claiming their position has legal support in precedent if they know it doesn't, etc.
More practically speaking, to ensure their client actually gets competent legal representation they would push their client to accept them presenting multiple legal arguments and not exclusively sticking to the narrative, allowing the lawyer to focus on the client's legal rights and doing what a lawyer should do (basically "the client does not concede on any point, but if the court finds X then we argue A and if it finds Y we argue B", offering legal arguments to "hypotheticals"), so you don't leave any important legal arguments from the opposing side unanswered.
Tldr, make sure that no matter what the court finds, you're making arguments to protect their legal rights and to ensure sentencing is fair.
And when a client is so unreasonable that their position can't be represented accurately in a legal manner without simultaneously contradicting the client, well screw that client π€·
Linux does this better by defaulting to files not being executable, versus Windows needing the downloading software to apply a specific "downloaded file" flag to trigger a notice about potentially unsafe files.
You could make a lot of the commands available by default much less dangerous. Stuff like requiring using protected screens more (like UAC and ctrl+alt+del) for enabling the risky stuff.
Also, sandboxing by default would do even more to prevent the worst dangers.