Honestly, I've never understood why people are saying kneeling is disrespectful.
People are generally saying that the kneeling is disrespectful because the following:
1. The kneeling protests began with Colin Kaepernick
2. Many of those kneeling has suggested they are doing it in solidarity with the protest and point Colin Kaepernick was doing.
3. Colin Kaepernick's original claims for why he was protesting was not due to "loss of life." Rather, it was because:
"I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color"
This does not give the impression to many that the kneeling is done as a means to "mourn a hurt of the country", but rather specifically to show disagreement and disrespect to a country that they believe "oppresses black people and people of color".
Indeed, the original claims for why the protests were happening...WHY the anthem and the flag specifically were the central point in time for the protests...was not because it was a moment where people would be focused on it (indeed, he did it for two games without anyone noticing or drawing attention to himself; it was a personal thing at first). It was not because of raising awareness. It was not because it provided a platform. It was SPECIFICALLY because of a desire to not show respect and veneration towards a symbol of a country he believed was oppressing black people.
It was inherently an act of disrespect, or...at best...a lack of respect.
Now people may agree with his point, disagree with his point, not care about his point, whatever. They can believe that other players agree with him, don't agree with him, are doing it not for his reasons but in support of him as a person, because of Trump, whatever. However you come down on those various things is irrelevant; based on how this started and the reasons stated, it shouldn't be difficult to understand why people view the kneeling as an act of disrespect, and it's not simply "MURICA!" type logic.