The 'assumption of truth' step doesn't require us to believe anyone who walks up and says "A ^ ~A". Rather, it says that you shouldn't immediately reject a philosophy because it disagrees with your prior notions.
The 'resolve contradictions' similarly doesn't mean that we have to overlook flawed claims. It's a tool to help learn an idea even if you don't get a perfect presentation of it. There may be a valuable concept available even if the person explaining it to you can't properly work through every detail.
As an example, most people who could talk to you about evolution can't explain the development of eyes, but that doesn't mean you should assume evolution is bunk when you hear about it. The principle of charity says "there might be a good reason here, whether or not they can provide it".
In short, the principle is an attempt to get value out of ideas you're presented with. That might mean you're engaging with a different idea than what you were actually presented with, but it gets you more insight. It's not something you want to use when faced with a concrete form of the document - it's not a reason to pass a bad-but-well-intentioned law.
He had a great story to go with this, but the TLDR is that the PoC is the safe choice when applied to engineering: give a true, best-faith effort to prove the opposing view correct. (And best-faith is important: you can not approach it with bias, lest you waste everyone's time.) If you're right, then you'll find an irrefutable flaw in the engineering, and if you're wrong you've learned something new.
If it sounds like a lot of effort, it is.
But this is also utterly win-win. It's a way of assuring that you've been careful. Avoiding the humiliation of hubris is great if a detail of the implementation was missed at first glance. But you also will inevitably more fully understand the problem when you've failed to implement the opposing view; it also puts you in the excellent position to graciously be on the same side as your opponent and now you can sway your now-ally-in-war in their reasoning. In either way, your goal must be to solve the problem, and not merely "win" political points.
Of course, there's crackpot theories and stupid ideas and foolish plans which should be dismissed with prejudice. But hopefully you're working in a professional environment where your coworkers really are trying their best to succeed. And even then, a serious engineer will still give the stupid ideas at least some (small) time of day, as you must have a reason for all decisions, even dismissals; as you become experienced, you'll be able to properly dismiss these faster and more precisely, but you'll still need to go through the process. That process is what separates the people who loudly proclaim they are smart and right from those who would testify in court they are right.
(Incidentally, this is part of the reason why I get immensely frustrated with "idea people", as it takes much more work to flesh out their half-assed ideas into full-assed ideas. Non-engineers don't get that there's a huge amount of effort to constantly take everything and everyone seriously.)