When used in the sense of "to command" in Syriac and CPA, the G stem clearly often has a less urgent or demanding sense than the D stem.
In AIOA p. 79 it is suggested that the early usage in the sense "to entrust, deposit" is a calque from Akkadian.
It is not at all clear that "to be deposited" must be interpreted as Ct in JPA rather than as Gt.
A recent study on Biblical Hebrew usages of this verb by S. Creason, "PQD Revisited" in Studies in Semitic and Afroasiatic Linguistics Presented to Gene B. Gragg (OI, U. Chicago: 2007), pp. 27ff. should also be consulted.