iserith
Magic Wordsmith
If what he thinks is based on a memory, it's an adjudicatable action.
That's a reach. Some might say an overreach, when judged by what the game says the DM's role is.
No, it's not. And frankly it's insulting that you to keep saying that. Perhaps you give up that part of your role, but we don't. The player has no ability to adjudicate his own attempts to recall lore, which every single memory brought up by the player is. The player can't get around actions by phrasing things as already done. Otherwise a player at a river can just say, "Once I'm across on my raft I look for the troll from the top of the tree on the far side of the river." and lo and behold, since he didn't declare an action, he automatically built the raft with no roll and made it across the river with no roll and climbed the tree with no roll. If the player says, "I remove the loot from the dragons body." does the dragon just end up dead with no fight?
In order to make this case, you have to prove that a character establishing what the character thinks is actually an attempt to recall lore. Which you haven't and can't do using the rules. But you shouldn't be insulted because anyone can add a table rule to the game to broaden the DM's role. That's a thing you can do and, it appears, have done. I wouldn't do it because I think the DM has enough power and I don't want to take anything from the players, but you're free to do so.