Altair didn't fail to notice the change in expression between the one Nate gave him and the one he gave Ari. Truly, Altair was used to his guildmates being wary of nobles. More than the other guilds, the Thieves Guild drew heavily from the lower classes—understandably, since many of them already had demonstrated an aptitude such things before they were even old enough to join the guild, just from years of living hand-to-mouth. Still, Altair didn't bother trying to win these types over in one-off interactions like this. Most of them wanted to be angry at nobles, and Altair didn't mind being exactly the type of asshole they expected him to be.
"I, too, will be in touch," Altair said loftily, making a point to check the contents of the bag, to ensure that it contained all that he expected, "assuming that these deliver all that you say they will." He had little doubt they would. He trusted Vivi's judgment completely. She was a kind woman, but she wouldn't suffer incompetence.
Altair was even a bit excited to get the locks home and begin taking them apart, not that he would let that be known to Nate; and then, he would begin thinking about the next project he planned to toss the machinist's way.