It is not clear as to what the mechanism God uses to harden hearts is; allowing such or in someway forcing such. It would be easy not knowing why God would want such for us to have difficaulty with this passage. With such passages it is best to give God the bennefit of our doubt and seek through for a more understandable why.
Why? Hearts tend to harden or soften on their own given situations whether reasonably our unreasonably. These peoples hearts had been hard and continue to be unreasonably hard to this day. Perhaps God knowing that their hearts would not soften (or only temporarily) set in motion the final hardening (atleast for this time). Neither do we know the demonic warfare occurring behind the scenes that God may have been cleansing out of the area.
It is clear that when God reveals such a massive addition to the faith HE does not put every apostle immediately into the loop; the matter was not conferred upon then implemented. It was implemented because of the way God brought it forth outside of the constructs of either man. Then it was conferred upon by the greater whole.
It appears that the Spirit did not directly have to tell them to send relief, they were able to determine that themselves. Perhaps He had impressed upon them, perhaps He had developed the desire in their hearts, but, the decision to do it was theirs.
They, the race at that time (either majority or all) journeyed in an attempt to remain one people to a place in the valley of Babylon where they could make one large city. It does not seem to be opposed at first by God until He saw what they were trying to build in it's midst.
Who does the Son reveal His Father to? Those who come to the Son toiling and heavy ladden in the convicting burdens of sin. Once relieved of such burden, having taken on His yoke humbly and with meekness, shouldering a sample of His burden, then one comes to know the Father. Such immense time released revelation is only by exchanging our burden for His Son's and carrying His Son's burden forward. It is not any other way around. The so called wise and prudent systematically avoid to see this.
2012 - pBiblx2 Field Wise Bible System Version 2.0.9d - GPL3