An update. The crew turned out to be a recent high school grad who is starting a landscaping business. I'm not his first client, but I can tell he's still learning the process. Overall him and his guys worked hard on the job (re-jointing about a million brick pavers in the front yard and back), which was nice. I had to give him a few pointers on how to level the pavers and they applied the sealant too early which caused some issues, but overall it's better than what it was.
Lesson learned on my part, though. Rookie mistake. They almost finished the job but needed to come back to finish a few spots in the backyard and seal, but I paid them the full balance after the first day. I'm sure they will be back (probably even today) but lesson learned never to pay the full amount until the job is 100% done as there is the random risk they just flee the job unfinished.