Fortunately, I think that the evidence for Seleukid Argyraspidae is clear enough that they were primarily elite "Makedonian-style" phalangites.
Thanks, Angadil, that clears things up.

Will the Seleukid Argyraspides be a phalanx unit in the future? If not, what is the rationale for portraying them as a javelin-throwing spear unit?

Just wanna know, that's all. :)

Ciao!