Lex did not immediately activate the Reboot token. Once he did that, he expected to be faced with a lot of simple and easy quests and he wanted to face them with 100% of his attention and focus, so he had to finish up everything else before that was done.
The list was not too long, but the key thing among them were the letters. Now that he felt no pressure about writing them, he had only two concerns when it came to them. The first was to ensure he didn't accidentally compromise his identity.
The more he interacted with Dao Lords, the greater the chance of that happening. But he'd also gotten a lot of practice doing it now, so the chances of him making a mistake were lesser - at least in letters. In person, the advancement of his Primordial Dao Body had actually increased the chances of him being discovered rather than helping him keep the secret.
