I think that's an interesting verse and something to think about. The Gurus lived their own lives, they were political leaders of a 15th-18th century panth, so of course we can't emulate them fully. Spirituality should also not be mixed with morality; while they are often heavily correlated, being a good person won't make you attain enlightenment per say and just meditation won't make you a morally rigorous person. Heck, this is why different spiritual teachers have different moralities; some are for free sex, some see it as a distraction. Some like the Sikh Gurus believed that it was better to defend yourself instead of let yourself be killed, others like Buddha believed you should sacrifice yourself before ever committing violence.
However, I think what made the Gurus powerful is that they did lead by example, that they led by practicing what they preached. They spoke about practicing good deeds, about dharma being morality, and they followed through on that. However, emulating the Gurus' lives isn't going to get you enlightenment; only their teachings. This is why what should matter to Sikhs is the GGS, not sakhis and supposed miraculous features of the Gurus.
Regarding polygamy, I've consistently been disappointed by Jagraj Singh's attitude on this. Despite the fact that he asserts that Guru Gobind Singh had three wives, the canon only officially records two: Mata Sundri and Mata Jito. Even among these, it's complex.
The biggest factor for why it seems like absolute bullshit is written in Sikh history itself. There is a tendency among Sikhs historically to dichotomize the Gurus into the "saintly" ones (1-5 and 9), and the other royal ones. Polygamy is attributed to Guru Gobind Singh, Guru Hargobind, and Guru Har Rai. While it is absolutely true that these Gurus broke new ground in adding royal traditions to Sikhi (more along the lines of Miri), the dichotomy is flawed. Guru Tegh Bahadur also kept a kingly-type darbar and fought in wars when he was young. Guru Arjun Dev Ji had political influence. It's very telling that ONLY the "royal" Gurus kept more wives while the saintly ones did not. Heck, one of the main charges against Banda Bahadur was that he tried to marry twice, something that infuriated the panth. The fact that it's lambasted in Bhai Gurdas's vaaran, i.e., the Bhai Gurdas that vehemently supported Guru Hargobind even when the latter was criticized, suggests that it has no place in Sikhi and we should question the historical basis of where it came up from. I remember another video where Jagraj Singh said that bani was subjective which is why it was okay for a kharku Singh to get two marriages...