Using ruby with a different reading (or even different kanji) to add nuance or clarify the meaning is a pretty common device in manga, books and lyrics.
Most often the words used are synonymous or closely related, e.g.: 宇宙{そら}
, 地球{ほし}
, or 瞳{め}
. (Usually the furigana is the actual reading and the kanji gives the nuance or selects one meaning from several possibilities.)
「i ~crossin' the star~」 by 木村{きむら}由姫{ゆき} has quite a few examples of this:
おとぎ話で覚悟を決めさせて ダレカじゃないこの想い[i]{愛}が聴こえる?
「天{あま}の河{がわ}で心揺れて 流れるまま[永久]{とわ}に触れて 瞬間{とき}の内{なか}で甘く熟れて」
星が描く場所に二人出会えたなら生まれ変わる
In some cases concrete words under placeholders help the reader grasp the context which is obvious to the speaker (e.g. 「学校{ここ}はプールがないから。」
or 「田中{あいつ}は来なかった。」
).
Sometimes even more elaborate schemes appear like the one in the 『星界の紋章』 (Crest of the Stars) books where the words written with Japanese kanji are given readings in the fictional [アーヴ語]{Barohn language}: 帝国{フリューバル}
, 士族{リューク}
. Scrapped Princess is another offender, except there the readings are English words: 竜機神{ドラグーン}
, 第五特務部隊{オブスティネート・アロウ}
. A recent example is the Toaru series (とある魔術の[禁書目録]{インデックス}
and とある科学の[超電磁砲]{レールガン}
).
In your case it seems the author is hinting that the meaning is used in figurative or ironical sense. It's somewhat difficult to tell more without context.