What is upward entailment or monotonicity increasing in english?

Is this how it works?

(1) a. All [workers ↓] [joined for a French dinner ↑]
(1) b. All workers joined for a dinner

A context is upward entailing (shown by [… ↑]) that allows an inference from (1a) to (1b), where French dinner is replaced by a more general concept dinner source: [link] (https://arxiv.org/pdf/1906.06448.pdf)

then, is it correct to replace (2a) to (2b)?
(2) a. [thieves ↓] [stole Salted butter, clarified butter, and European butter ↑]
(2) b. thieves stole butter