Is it really this easy? Just check the bool from map.h?

Yes, although you need definitions in the talker classes to specify. Something like this, for every class of talker that you intend to be able to use this function.

talker_character::is_wall_adjacent() const {
return get_map().is_wall_adjacent( me_chr_const->pos_bub() );
}

Note that the function name is somewhat misleading. It does NOT check for walls, it checks if the tiles are impassable.