"The uncomfortable, irrefutable truth is that this decision is a disaster for women's sport," Morgan wrote.
"By supposedly promoting 'equality' with the inclusion of a transgender weightlifter, the Olympics have created a shocking new inequality – and everyone with half a brain knows it."
Hubbard had competed in men's weightlifting competitions before transitioning in 2013 but didn't compete internationally.
Her gold medal wins at the 2019 Pacific Games in Samoa, where she beat Samoa's Commonwealth Games champion Feagaiga Stowers, sparked outrage in the island nation.
Australia's weightlifting federation tried to block Hubbard from competing at the 2018 Commonwealth Games but it was rejected by organisers.
"Women born to female biological bodies are at a massive disadvantage to transgender women like Laurel Hubbard born to male biological bodies," Morgan wrote.
"How can it be right that Australia's fine female weightlifter Charisma Amoe-Tarrant will now miss out on a dream appearance at the Olympics because Hubbard took her place?
"Why should Samoa's Feagaiga Stowers, who Hubbard beat to gold at the 2019 Pacific Games, now again have to face an opponent with such an unfair advantage?"
NZOC CEO Kereyn Smith said Hubbard will be welcomed to the New Zealand Team.
"As well as being among the world's best for her event, Laurel has met the IWF eligibility criteria including those based on IOC Consensus Statement guidelines for transgender athletes. We acknowledge that gender identity in sport is a highly sensitive and complex issue requiring a balance between human rights and fairness on the field of play.
"As the New Zealand Team, we have a strong culture of manaaki and inclusion and respect for all. We are committed to supporting all eligible New Zealand athletes and ensuring their mental and physical wellbeing, along with their high-performance needs, while preparing for and competing at the Olympic Games are met."
Morgan said in his column that if Hubbard wins gold in Tokyo "it would end the Olympic dream".
"New Zealand's infamously woke government and the country's top sporting body have backed Hubbard's inclusion," Morgan said before wrongly calling Kereyn Smith "Mr Smith".
"I don't blame Hubbard for any of this, by the way," Morgan went on.
"It's not her fault that she's been allowed to compete in the world's greatest sporting event with such an obvious physiological advantage over her rivals.
"If Laurel Hubbard wins gold in Japan, it will be the end of the Olympic dream as we know it ...
"As I've said many times, I support transgender rights to equality and fairness – but not when those rights damage women's rights to equality and fairness.
"This is unfair and unequal.
"And it's not 'transphobic' to say this, it's just common sense."
Hubbard may not be the only trans athlete to compete in Tokyo. BMX rider Chelsea Wolfe has been named as an alternate in the USA team while Canadian footballer player Quinn is a chance to be named in the women's squad.
After being named in the Olympic team yesterday, Hubbard said she had been "humbled by the kindness and support".
"When I broke my arm at the Commonwealth Games three years ago, I was advised that my sporting career had likely reached its end. But your support, your encouragement, and your aroha carried me through the darkness.
"The last 18 months has shown us all that there is strength in kinship, in community, and in working together towards a common purpose. The mana of the silver fern comes from all of you and I will wear it with pride."
Olympic Weightlifting New Zealand President Richie Patterson said Hubbard has worked extremely hard to qualify for the Olympic Games.
"Laurel has shown grit and perseverance in her return from a significant injury and overcoming the challenges in building back confidence on the competition platform," said Patterson.
"Laurel is an astute student of the sport and technically very good with the lifts. We look forward to supporting her in her final preparations towards Tokyo."
