I've seen this before. Your proof is a single person's opinion. Note that it is an opinion, with no evidence or data to back it up. It contains numerous tropes of IDF apologists and is written by a person who has a long history of opposing any investigations into the actions of the military and having generally right wing, militant, pro-European and anti-Muslim views. the letter appeals only to those who want to believe it.
More tragic than funny but it is human nature. Propaganda mills like PragerU exist because they work. People are happy to pick up other people's opinions because it saves them doing the hard work of forming one themselves. Lots of people believe things that are patently false, from religion to pseudo science to flat earth. Just believing something because it aligns with your existing opinions and prejudices doesn't make it true, it makes it confirmation bias.
The source of this shoddy opinion is PragerU, a very well funded and openly right wing, Christian, pro-Israel media outlet. It is literally paid my its wealthy right wing ultra rich donors to publish one sided content that pushes the donors' views for the donors' benefit. It is as far from a neutral objective source as you can get.
Here's their annual report from last year for a glimpse at their bias: https://downloads.ctfassets.net/qnesrjodfi80/5CKH6Ji47c5yxhv...
Funny that "one person's opinion" happens to be shared by a lot of people though