Some grammatical and exegetical readings take one particle as approximating the meaning of another. The passage raises the claim that in can mean idha in certain cases, but objects that this can obscure the underlying contrast.
An alternative is to retain in’s original distinction and explain an unusual occurrence through rhetorical assumption, feigned doubt or strategic framing. This preserves a reason for selecting the particle.
Nevertheless, interpretations differ by passage. No single explanation should be imposed without considering the surrounding evidence and the reported scholarly positions.