The offer to help the Israelites rebuild the temple does not appear to be something that an enemy would do. The people of Israel would also find this offer very attractive. They do not have all the skills needed to build the temple (that is why they had to hire masons and carpenters in Ezra 3:7), and if you have people helping you, you have more money to spend on decorating the temple. From a human perspective, it seems strange that the people of Israel would refuse help from people that kindly and willingly offer to help them (Ezra 4:3).1
2 they approached Zerubbabel and the heads of fathers’ houses and said to them, “Let us build with you, for we worship your God as you do, and we have been sacrificing to him ever since the days of Esarhaddon king of Assyria who brought us here.”