The path to anti-capitalism is not necessarily a straight line. People can reach it from many different, winding roads. Also, people are complex, we can hold a diversity of thoughts, on numerous different topics, simultaneously.
It should also be noted that anti-capitalists are not a monolith or hive-mind. Some anti-capitalists are relatively conservative, especially by Western, liberal standards. In fact, many Marxists are quite opposed to liberalism in general.
It may be that this young man isn't an anti-capitalist after all. It doesn't change my support. He has helped further expose the inhumanity of capitalism, either way.
Liberalism is a political and moral philosophy based on the rights of the individual, liberty, consent of the governed, political equality, the right to private property and equality before the law.
There are many Marxists who are opposed to much, if not all of these things. They are unequivocally opposed to the right to private property. That is foundational to Marxism. Marxists-Leninsts specifically do not seek the consent of the governed, nor are they committed to the protection of individual rights, liberties, or political equality. You might think that makes them fascists, but they don't consider themselves fascists. They do, however, consider themselves anti-capitalists.