Wouldn't simply adding a zero check work?
// Hold event = show tooltip
if (tooltipDelay != 0f && currentTouch.deltaTime > tooltipDelay) // <-- here
{
if (currentTouch.pressed == currentTouch.current && mTooltipTime != 0f && !currentTouch.dragStarted)
{
mTooltipTime = 0f;
currentTouch.clickNotification = ClickNotification.None;
if (longPressTooltip) ShowTooltip(currentTouch.pressed);
Notify(currentTouch.current, "OnLongPress", null);
}
}