You're very right to call Ho Chi Minh a Vietnamese nationalist and an anti-colonialist. But, the dude absolutely loved Lenin.

At that time, for those youths of our age, Nguyen Ai Quoc (Ho Chi Minh) had become our ideal, the object of our dreams. In the years 1926-1927, while the student movement in Hue was developing due to the great impact of the Russian and Chinese revolutions, we often called on l'han Boi Chau in Hue where he had been brought from Hanoi and kept under forced residence. Often he told us about world events. On the walls of his house were portraits of Sun Yat-sen, Lenin, and Sakyamuni.

This is kind of a funny detail, but Ho Chi Minh also named a stream that he and other members of the CPV lived near when they were in hiding from the French "Lenin Stream". He really liked that guy. Other Vietnamese Communists liked him as well.

Ho Chi Minh could be called a Marxist-Leninist (although it's important to note that he had taken little inspiration from Stalin, who had created Marxism-Leninism). Perhaps it's better to call him a Marxist and a Leninist. He was initially attracted to Leninism when he was in France, upon learning that Lenin was speaking out against imperialism and colonialism in his work: Imperialism: The Highest Stage of Capitalism. It's important to note that though he was a Vietnamese nationalist, he and the Communist Party of Vietnam feuded with (and would later purge) the Việt Nam Quốc Dân Đảng (the Kuomintang-aligned Vietnamese nationalist party). Chiang Kai-Shek had actually arrested Ho Chi Minh in China and released him on the deal that the CPV would cooperate with the VNQDD.

Maybe the best answer to your question is: He was attracted to communism because he was an anti-colonial nationalist.

Citations:

Võ, Nguyên Giáp, and Russell Stetler. 1970. The military art of people's war.