Atalanta did not had a chance to win the league anyways, if they won all three, that would be nine more points and they are at 58 points right now, if they had 9 more points that would be 67 points and nearly where Inter is, and Inter has 68 points, so there would be only one gap. So even in a scenario where they won all, they are still not at the top, and when Napoli wins, that would mean even Napoli has the same points as them.
Atalanta needed a perfect record on all those games to be even in the discussion, let alone be champions. If you are that far away, then it would be unfair to consider them a title contender. What they have going for them right now is the fourth place, if they fail to do better, Bologna is right there.
You’re right, Atalanta did not have a chance to win the league again this season, even if they beat Lazio to secure the 3 points, because Inter Milan leads them by ten points, which Atalanta will find difficult to reduce with the remaining games in the season. If they win the game, they will be 7 points behind the league table, however, they failed to at least draw at home, and Lazio moved up to sixth place with the three points.
However, Napoli failed to take the lead against Bologna, Napoli drew an important game that could put them one point behind Inter Milan, and when Napoli took the lead in the first half, I assumed that Inter Milan would have a difficult time returning to the top because they are playing in the Champions League, whereas Napoli can only play in the league for the rest of the season. But they are now three points behind Inter.