No. The archer will not try to attack ranged, and will therefore not have any disadvantage to lose. As the archer does not have any attack, he/she will move as if he/she had a melee attack.
The rule book, page 30 wrote:
If a monster has a move but no attack afterward as part of its ability card, it will use its movement to get as close as possible to its focused target (determined as if it had a melee attack), moving along the shortest possible path to enter a hex adjacent to its focused enemy.