First, “does warrant” and “warrants” are equivalent, but “does warrants” contains two verbs at war.

As far as the infinitive goes, I would expect that “warrant” simply requires a gerund rather than an infinitive as an object that is a verbal. “Doesn’t this post warrant pinning?” “Doesn’t this post warrant being pinned?”

Both “pinning” and “being” in these examples are gerunds (-ing form of the verb). In many cases the gerund and the infinitive are interchangeable as objects, but not for every verb.

In the case of “I want to be happy,” 'want" is an example of a verb that takes an infinitive as a verbal direct object.

Does this help?