Going by the LSJ, “Act. intr. in sense of the Pass.,” could he have used ἔστειλα just as well here? Is there any difference of meaning between ἔστειλα and ἐστάλη here?
Interesting question.
This is one of the passages cited in LSJ under this head (4.147):
τὸν δὲ αὐτὸν τοῦτον χρόνον Θήρας ὁ Αὐτεσίωνος τοῦ Τισαμενοῦ τοῦ Θερσάνδρου τοῦ Πολυνείκεος ἔστελλε ἐς ἀποικίην ἐκ Λακεδαίμονος:
Here ἔστελλε seems to mean that Theras set out (imperf. active) on an expedition to colonize the island of Thera. I think the use of the active suggests that Theras didn’t just set out Thera alone, but that he went out with a party of colonists, which is perhaps understood as the direct object of the transitive verb.
In the next chapter, ἐπὶ τούτους δὴ ὦν ὁ Θήρας λεὼν [Ionic for λαον] ἔχων ἀπὸ τῶν φυλέων ἔστελλε, – he had a [group of] people from among the Lacedaemonian clades and set out with them [with himself along], i.e., went out with them on an expedition to colonize Thera.
Herodotus 5.124-5:
πρὸς ταῦτα δὴ ὦν συγκαλέσας τοὺς συστασιώτας ἐβουλεύετο, λέγων ὡς ἄμεινον σφίσι εἴη κρησφύγετόν τι ὑπάρχον εἶναι, ἢν ἄρα ἐξωθέωνται ἐκ τῆς Μιλήτου, εἴτε δὴ ὦν ἐς Σαρδὼ ἐκ τοῦ τόπου τούτου ἄγοι ἐς ἀποικίην, εἴτε ἐς Μύρκινον τὴν Ἠδωνῶν, τὴν Ἱστιαῖος ἐτείχεε παρὰ Δαρείου δωρεὴν λαβών. ταῦτα ἐπειρώτα ὁ Ἀρισταγόρης. Ἑκαταίου μέν νυν τοῦ Ἡγησάνδρου, ἀνδρὸς λογοποιοῦ, τουτέων μὲν ἐς οὐδετέρην στέλλειν ἔφερε ἡ γνώμη, ἐν Λέρῳ δὲ τῇ νήσῳ τεῖχος οἰκοδομησάμενον ἡσυχίην ἄγειν, ἢν ἐκπέσῃ ἐκ τῆς Μιλήτου:
Aristagoras suggests that if the mutineers are driven out of Miletus, he should lead them as a group to settle [ἄγοι ἐς ἀποικίην] either in Sardis or in Myrcinus. But the opinion of Hecataeus was prevailing[ἔφερε ἡ γνώμη] that they should set out on an expedition [στέλλειν] to neither of these.
I think that the imperfect and aorist active, when used intransitively, imply going in a party, and both instances in Herodotus involve a wholesale resettlement by a group of people in a new location. There doesn’t seem to be a similar implication of a group resettlement in the case of Arcesilaus and Periander, although it can be understood that they went or started to go with a party of retainers.
In sum, looking beyond dictionary definitions at Herodotus’ actual usage, I think that the “intransitive” use of active στελλω implies setting out or going in a group (and perhaps with the purpose of resettlement), whereas the medio-passive and 2d aor. passive don’t have those implications. But I would probably want to look at more instances of στελλω in Herodotus, and I could be wrong.
mwh will surely provide some help here.