When would a confession be invalid? When the penitent is not a baptized person; then the penitent is under an excommunication the lifting of which is reserved to the Bishop or the Apostolic See; when the penitent lacks awareness of the gravity of a sin; when he does not express remorse, or an intention of amendment.
"To acknowledge ones sins to recognise one as being a sinner, capable of sin and inclined to commit sin, is the essential first step in returning to God" (Pope John Paul II, Reconciliatio et Penitentia, (1984), n.13). Were it not possible to withhold absolution the very integrity of the act of Christian conversion would be undermined.
"God pardons nothing to those who pardon themselves everything," declared that saintly confessor, the Curé of Ars. Purporting to absolve an unrepentant penitent brings no one to this realisation. It will be a rare case, but when a person confesses a felony, requiring him to go to the police before absolution may be the only way to ascertain that he is actually repentant.
The absolution, however, is not always, and in every circumstance, and in every case, dependent upon turning one’s self into authorities.
That was my point to wideawake. Absolution is given, under all the reasons you say, but does not require turning one’s self in to authorities in every circumstance.