There were actually several reasons why Riley felt the need to go back to work.
For one, he really needed to get back on his feet and figure out his version of the new normal. While it was easy to stay holed up with Kael and their family, it would literally do no good for anyone but the bad guys.
Second, he wouldn't be able to properly train at the dragon estate unless he wanted to advertise his existence to all the other dragons.
And he would have to say a big hell no to that.
Ideally, his return should've been welcome news for the dragonkind, but personal experience and historical data would suggest otherwise. If anything, he'd likely end up being chased to oblivion if they were to find out about him now.
Lastly, there were a few things he needed to prepare before attempting to go into the business of crypt diving.
