He's not a Stih (anymore.). And it was an interesting contrast to see him looking for hope, while Ezra was instead looking for a way to destroy his enemies.
Hope is interesting for a former Sith, though Hope for what exactly?
It seems clear from previous interactions that much of his drive for revenge is focused on the remaining Sith and the inquisitors. He wasn't BETRAYED by Obi-Wan and might even sympathize with him a bit.
Paired with Ezra's desire (someone that is a key to destroying the Sith) I could see an awkward alliance in the future.
If I had to guess -- Maul wasn't looking specifically for Obi-wan, but for the "hope" to destroy to the Sith. What they saw was a vision of Luke, but he likely also saw Obi-wan in the vision. I'm assuming Maul plans to kill Obi-wan, find Luke, and raise him as a Sith apprentice to take out Vader and the Emperor.
Sidious used Maul to lure out Mother Talzin to be able to finally kill her for good. In the process the Shadow Collective disbanded and Maul lost all the power he had over anything. He was pretty much on his own and Sidious no longer saw him as a threat to his plans and no longer cared about Maul.