The word "unassailable" means something that is impossible to doubt, attack, or defeat. It describes a situation or a person's position that is very strong and cannot be easily challenged or disputed. Full definition
That was followed by two clean sheets and wins and an apparently unassailable lead in the home tie with Anderlecht, but we all know what happened next and the same thing just happened today, our defending as a team just disappearing and it now seems we are back to square one again. (justarsenal.com)
How do you suppose this type of information reflects on those rookies who already have an uphill battle to fight to land a client when they're met with a the potential client who, because they have your erroneous chart, thinks they're armed to the teeth with unassailable facts because someone of your stature published it? (remonline.com)