Typically, when a performer is instructed to swing something in this meter, it is the upbeats and only the upbeats that are swung, which would include all upbeat 8ths, and any upbeat quarters or dotted quarters. Everything else either lands on the beat or is played as is. So, I would play the duples in this example straight, as a contrast to the swing feel.
If this momentary departure from the underlying meter were intended to be swung, the composer/arranger really needs to write it in such a way that it is unambiguous. The common way to make this happen as two against three, where the two's are meant to be swung would be to simply write the full 3/4 measure as quarter, eighth, quarter, eighth, i.e., each pulse of two now consists of a quarter + eighth or three eighths total, and this, if strictly adhered to, would indeed swing, more or less, depending on the tempo > dah-do-dah-do....
As written, the duples are notated correctly, i.e., two bracketed quarters in the space of one dotted quarter, similar to the way three bracketed quarters replace two quarters. Another way to write this would be as four dotted eighths in a row and no bracket.