stutter, speak frankly
謇 centers on speech that is blocked or direct: stuttering as a physical interruption of words, and speaking frankly as pushing past hesitation to say something plainly.
謇 combines 言 (speech) with a phonetic component derived from 寒 (cold), suggesting speech that is frozen or blocked, hence stuttering. The extension to frank speech may come from the idea of breaking through that blockage.
Under a roof (宀), cold (寒-like upper part) makes your words (言) freeze and stutter. But when you push through the cold, you speak frankly.
For ケン, imagine a person named Ken who stutters when he's cold, but then speaks frankly once he warms up: Ken -> ケン.