It seems pretty straightforward. Any work like that history makes lots of statements that, taken together, when you're done reading, amount to a conclusion. If you take just one of those statements in isolation and it leads to a conclusion opposite to the one you'd have come to taking all the statements into consideration, you've taken that statement out of context.

The history of Bethlehem Steel is overwhelmingly about the excesses and abuses of management. The thread about Bethlehem's labor relations emphasized countless times the brutal conditions and low pay of Bethlehem workers. The history was in no conceivable way trying to make the point that unions killed Bethelehem.

It was around 1959 that the workers started to turn things around, but even then the history pointed out that management, thinking it could ride the gravy train forever and that it could raise prices any amount to cover labor costs, made a number of foolish agreements with the union. The most notable one was Clause 2B, which was essentially the Featherbedding Forever clause. It's interesting to note that the one sentence you took was from that section, and it was about future benefits for which the Clause 2b negotiations set the precedent. 13-week vacations and "UN Day" were still in the far future and had nothing to do with the events described in the history.

In other words, that sentence was doubly out of context, being not only inconsistent with the whole story, but not even a part of the story.

That's a serious context deficit.