Joseph married Helen Mar Kimball just a few months short of her 15th birthday. He had not been pursuing her. It wasn't even his idea to marry her. Her father, Heber C. Kimball, requested that she be sealed to Joseph. There is no evidence that the marriage was ever consummated.
Is there evidence that it wasn't?
The source that the blog links to quotes Kimball as saying that her father "offered her to" Smith.
A quick googling finds me other LDS sources that excuse the marriage on the grounds that it wasn't unheard of at the time for 14-year-olds to be married off, not on the grounds that the marriage was never consummated.
From my perspective, the mere fact that a marriage happened is a strong sign that sex probably happened, too.
In point of fact, she continued to live at home with her parents after the sealing.
Not really surprising, since polygamy was illegal in Missouri.
Less than two years later, she married a young man she'd fallen in love with. They had eleven children together.
From what I read, it was about 2 years from her marriage to Smith until Smith's death, then about 2 years from Smith's death until Kimball's remarriage.
Remarriage of a widow isn't a sign that the widow's first marriage wasn't consummated.
In the same document you quoted from, Helen Mar Kimball stated many years later that God "[knows] better than ourselves what will make us happy. I am thankful that He has brought me through the furnace of affliction & that He has condesended to show me that the promises made to me the morning that I was sealed to the Prophet of God will not fail & I would not have the chain broken for I have had a view of the principle of eternal salvation & the perfect union which this sealing power will bring to the human family & with the help of our Heavenly Father I am determined to so live that I can claim those promises." Does this sound to you like it came from a woman who believed herself to be a victim of pedophilia?
It's certainly consistent with something from someone who agreed to sex at an age we now recognize as too young for informed consent and who spent the whole rest of her life steeped in an environment that reinforced the idea that she made the right decision.
She also wrote a poem quoted in that same document, "The step I now am taking’s for eternity alone." She knew full well that the marriage was not to be for this life. Her life after the sealing was not impacted in any way by the event.
Either that or she was referring to her reasons for agreeing:
I will pass over the temptations which I had during the twenty four hours after my father introduced to me this principle & asked me if I would be sealed to Joseph, who came next morning & with my parents I heard him teach & explain the principle of [p. 1] Celestial marrage-after which he said to me, “If you will take this step, it will ensure your eternal salvation and exaltation & that of your father’s household & all of your kindred.
This promise was so great that I will-ingly gave myself to purchase so glorious a reward.
I see no reason to assume that this line in her poem must have meant "my marriage wasn't supposed to really begin until after my death" and couldn't have meant "the only reason I married him was to secure my family's eternal salvation."