I do Urban Exploration, which involves sneaking into abandoned places without permission (trespassing).
I do a version of that, but less trespassy: Utah is home to some truly amazing abandoned Cold War installations. The joys of living in a state where you can set off nuclear bombs and no one notices...
But in my younger days I could have introduced you to Vance Barton, from Facilities & Engineering, who had an impressive array of coveralls, ID badges, and clipboards.
Yep, social engineering is the easiest way in.

I did a fair bit of penetration testing in my consultancy days, dress appropriate and tailgate worked very, very, often.
Same here. Since we do a fair amount of sensitive work, all our employees get an extremely rigorous security training regime that involves things like resisting social engineering hacks. In doing so, we inadvertently learn ways to circumvent some, let's say, lesser-endowed security regimes. But from time to time we do truly interesting things that require us to have armed guards at our installations. Those are the fun times.
The point is that we're not going to believe any argument that can't have as its premise the notion that the alleged saboteurs placed the alleged explosives exactly where they wanted them to be. Now this may be a straw man, since Vixen has noted that the samples examined were taken from critical places surrounding the bow visor and car ramp. She has also proposed that sinking the ship may not have been the intent. It happened, yes, but hypothetically the saboteurs may have had some other goal in mind.
The problem is there really is no rhyme or reason to the explosive placement inferred from the findings as we have them. "We found one kind of evidence here," and "We found a different kind of evidence there," but there's no holistic big picture that makes sense. This leaves Vixen having to scramble to throw together a tortured narrative whose only virtue is fitting the picture of evidence as she sees it. Look! The shape of the water exactly fits the pothole! What a miraculous coincidence! All those kinds of conspiracy claims boil down to circular reasoning.
Literally all of that argumentation is trumped by having the actual chunks of the ship from which these minute samples were taken. The unstated nail that Vixen is hammering away at is the notion that metallurgical examination is singularly dispositive. It isn't. It's one piece of the puzzle, but a better piece is macro scale examination of the structural elements allegedly involved in demolition. Braidwood could only do that via grainy, shadowy video. We now have high resolution photographs taken from every angle of the actual parts of the ship raised to the surface. That's
far more dispositive.
Imagine that you send a sample of an organism to a lab for DNA analysis, and they come back saying it's a leopard. Okay, you think; a little strange, but the analysis is reasonably sound on its face. But when you get to look at the actual organism, and it's quite obviously an elephant, you don't insist on the reliability of the DNA analysis and the eminence of those who performed it as dispositive of the identification of the animal. Yes, you should look closer, but the goal is to figure out what made the DNA analysis go wrong. The preponderance of other evidence answers the big question.