Realise that strength is not an absolute, it is subjective term and many 'cheat' methods can and are used when demonstrating strength.
Um. Sorry, but it is an absolute. You either lift a weight or you don't. It's not like bodybuilding or a beauty pageant, where the winner is judged on a vague, shifting, morphing set of guidelines (not standards).
In contrast, the Arnold's just ran with some 460-470+kg weights were lifted in the strongman deadlift session. The lifts were done within the standards/rules/guidelines of strongman. So, those lifts were not subjective. They either locked out or didn't. It had nothing to do with a muscle looking "denser" or "fuller" or "had more flow", or where a competitor in a bikini had a "great personality".
It doesn't matter if a lift is easier for a person of a given physique performed in sumo fashion or easier of a different physique to do it conventional, or something in between. If it is performed within the rules, it counts. Just because a football bounces 5 times before dribbling through the uprights doesn't mean it's not a goal. The manner of how the ball got there is irrelevant according to the rules.
So, strength, within powerlifting, strongman and weightlifting (or any of the other strength sports) does deal with absolutes. Even the records are absolutes, recorded in exact numbers using calibrated weights (PL & WL).