The author describes the safety-valve thesis as a myth because

The 'safety-valve' thesis, popularized by Lala Lajpat Rai and later R.P. Dutt, suggests that A.O. Hume founded the Indian National Congress to provide a safe outlet for Indian discontent and prevent a violent uprising against British rule [2]. However, modern historians like Bipan Chandra describe this thesis as a 'myth' because, upon examining available historical materials and the 'Seven Volumes' of secret reports cited by Hume, they found no evidence of such a conspiracy [t6][t9]. The author concludes that the thesis does not hold ground because the Congress was actually the result of a growing national movement and the urge of politically conscious Indians to establish a national organization for political advancement [c3][t2]. Instead of being a British tool, the Congress was an indigenous effort by Indian nationalists who used Hume as a 'lightning conductor' to avoid early suppression by the colonial state [c2][t6].

Sources

1. [1] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 11: Indian National Congress: Foundation and the Moderate Phase > Was It a Safety Valve? > p. 248
2. [2] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 11: Indian National Congress: Foundation and the Moderate Phase > Summary > p. 256