In case anyone came across this forum post with a particular use case like mine (e.g. seeking to a label time with sped-up playback), I used a TweenMax.to() call instead of TimelineMax.tweenTo():
function quickSeekToTimeLabel( timeline, label, duration ) {
TweenMax.to( timeline, duration || 0.2, {time: timeline.getLabelTime(label)});
}