Can someone please explain “…more Stalinist than Leninist” because from my years of experence being an ML this sentence is absolute gibberish

This is trotskyist political view, considering how much time they spent agitating, it was somewhat accepted by the radlib part of mainstream. Btw. it's telling how of entire ton of trotskist propaganda mainstream accepted exactly the anti-AES parts.

Second their citation for the Uyghur genocide, while I cannot read the book to find its sources, is written by someone who worked for 7 years is USAID for the former USSR “managing democracy, governance, and human rights programs” he is known for his “… comments on current events in the media related both to the situation of the Uyghur people in China …” and is an open critic of the belt and road initive in his open seminars,

You can find the source on libgen. Here's the sources for the preface:

1 Mamatjan Juma and Alim Seytoff, ‘Xinjiang Authorities Sending Uyghurs to Work in China’s Factories, Despite Coronavirus Risks,’ Radio Free Asia (27 February 2020).

2 SCMP Reporters, ‘China Plans to Send Uygur Muslims from Xinjiang Re-Education Camps to Work in Other Parts of Country,’ South China Morning Post (2 May 2020).

3 Keegan Elmer, ‘China says it will ‘Normalise’ Xinjiang Camps as Beijing Continues Drive to Defend Policies in Mainly Muslim Region,’ South China Morning Post (9 December 2019).

4 Erkin, ‘Boarding Preschools For Uyghur Children “Clearly a Step Towards a Policy of Assimilation”: Expert,’ Radio Free Asia (6 May 2020).

5 Gulchehre Hoja, ‘Subsidies For Han Settlers “Engineering Demographics” in Uyghur-Majority Southern Xinjiang,’ Radio Free Asia (13 April 2020).

So... SCMP and RFA.

And the first ten sources for the introduction:

1 Emily Feng, ‘China Targets Muslim Uyghurs Studying Abroad,’ Financial Times (1 August 2017).

2 See Adrian Zenz and James Leibold, ‘Xinjiang’s Rapidly Evolving Security State,’ Jamestown Foundation China Brief (14 March 2017); Magha Rajagopalan, ‘This is What a 21st Century Police State Really Looks Like,’ Buzzfeed News (17 October 2017).

3 Adrian Zenz and James Leibold, ‘Chen Quanguo: The Strongman Behind Beijing’s Securitization Strategy in Tibet and Xinjiang,’ Jamestown Foundation China Brief (21 September 2017).

4 Nathan VanderKlippe, ‘Frontier Injustice: Inside China’s Campaign to “Re-educate” Uyghurs,’ The Globe and Mail (9 September 2017); HRW, ‘China: Free Xinjiang “Political Education” Detainees’ (10 September 2017); Eset Sulaiman, ‘China Runs Region-wide Re-education Camps in Xinjiang for Uyghurs and Other Muslims,’ RFA (11 September 2017).

5 Alexia Fernandez Campbell, ‘China’s Reeducation Camps are Beginning to Look Like Concentration Camps,’ Vox (24 October 2018).

6 See ‘Inside the Camps Where China Tries to Brainwash Muslims Until They Love the Party and Hate Their Own Culture,’ Associated Press (17 May 2018); David Stavrou, ‘A Million People Are Jailed at China’s Gulags. I Managed to Escape. Here’s What Really Goes on Inside,’ Haaretz (17 October 2019).

7 See Amie Ferris-Rotman, ‘Abortions, IUDs and Sexual Humiliation: Muslim Women who Fled China for Kazakhstan Recount Ordeals,’ Washington Post (5 October 2019); Eli Meixler, ‘“I Begged Them to Kill Me.” Uighur Woman Tells Congress of Torture in Chinese Internment Camps,’ TIME (30 November 2018); Ben Mauk, ‘Untold Stories from China’s Gulag State,’ The Believer (1 October 2019).

8 Shoret Hoshur ‘Nearly Half of Uyghurs in Xinjiang’s Hotan Targetted for Re-education Camps,’ RFA (9 October 2017).

9 Sean R. Roberts, ‘Fear and Loathing in Xinjiang: Ethnic Cleansing in the 21st Century,’ Fair Observer (17 December 2018).

10 See Zenz and Leibold, ‘Xinjiang’s Rapidly Evolving Security State.’

Zenz, RFA, and Financial Times.

Not exactly promising.