DUP leader Arlene Foster has declined an invitation to meet the pope at Dublin Castle, issued by the Irish Government, because she will be on a family holiday.

This is an acceptable reason for non-attendance. UUP and Alliance leaders Robin Swann and Naomi Long are also unavailable and this has caused no offence, although Swann’s prior engagement at a loyal order parade in Larne has caused amusement, being the most Protestant double-booking imaginable.

Swann and Long are sending delegates in their place, however, while Foster is sending nobody and has not explained why. This is an unmistakable snub. The DUP has a large leadership team plus dozens of present and former portfolio-holders, scattered across three parliaments. They cannot all be on holiday on the last weekend in August.

There is some question over who is being snubbed. Foster has previously said she would meet the pope if he visited Northern Ireland as a head of state, indicating some equivocation over his role as head of the Catholic Church, but no fundamental Paisleyite objection to an encounter with the Antichrist.

There remains an enormous appetite in Northern Ireland for symbolic acts of rapprochement

So the Irish Government may be the problem – the DUP and Fine Gael are barely on speaking terms and there is quite a difference between greeting a visiting dignitary on home turf and being summoned to pay homage in the enemy capital.

There may also be an extent to which Foster is being snubbed herself.

DUP assembly member Jim Wells, who has fallen out with the party and is currently speaking his mind, has told the Belfast Telegraph most of the DUP leadership will be at the parade in Larne – it is an important part of the Orange calendar – while others across the party would have “great difficulty” meeting the pope for theological reasons.

The implication is that Foster is too weak to despatch a delegate, as she dare not upset the Orangemen by sending somebody close to her, while anyone else might simply refuse to go.

Whatever the precise mix of factors, the DUP’s no-show is out of tune with Foster’s recent outreach efforts and this has been widely noticed.

DUP leader

The DUP leader has made halting attempts over the summer to engage with the GAA and gay rights groups, yet now her party is squandering a priceless opportunity to show respect to the Catholic and nationalist population, in a manner so blatant as to cause unavoidable insult.

Foster almost seemed to acknowledge this while sending her regrets. A DUP spokesman said she “appreciates the invitation” – from the Irish Government – and “she particularly acknowledges the significance of this event for many Roman Catholics in both the Republic of Ireland and Northern Ireland.”

So why no delegate and no explanation? It keeps coming back to weakness. The DUP would inevitably have been denounced in Orange halls and from Free Presbyterian pulpits, and Foster does not appear able to run that minor risk for any reward, despite knowing she needs to reach out to save her leadership, devolution and perhaps the union itself.

This might seem like a lot to read into one papal audience. Nationalists do not appear that angry at the DUP leader – wearily, they expect no better, and many are now conflicted about the Church themselves.

Foster’s Sinn Féin opposite number at Stormont, Michelle O’Neill, is also unable to meet the pope, due to a broken leg. Declining her invitation, she addressed the scandal of clerical abuse in forthright terms.

However, there remains an enormous appetite in Northern Ireland for symbolic acts of rapprochement. There have been three such moments since Stormont collapsed: Ian Paisley jnr thanking Martin McGuinness for his leadership and friendship to the Paisley family; Foster and O’Neill shaking hands at McGuinness’s funeral; and DUP and Sinn Féin former ministers Edwin Poots and John O’Dowd speaking of the need for reconciliation, after Sinn Féin’s Barry McElduff was accused of mocking the Kingsmill massacre. All provoked an outpouring of public emotion. Such acts might not sway a single vote for Sinn Féin and the DUP but they demonstrate the desire for agreement amid the fog of anger, making agreement easier to reach.

Meeting the pope could have been another such a moment, in large part because it is the only unionist gesture comparable to McGuinness’s 2012 handshake with the Queen. The sense among republicans in particular that this has never been reciprocated, and that McGuinness had thus been made to look a fool, was no small matter in Stormont’s collapse – it was voiced strongly to the Sinn Féin leadership by party members.

Strictly speaking, unionists have reciprocated: Queen Elizabeth’s opposite number is the Irish president and the DUP meets Irish presidents often, predating 2012. President Higgins and Foster’s predecessor Peter Robinson were among the seven people in the room when McGuinness first met the Queen.

But everyone knows that is not the same. This weekend was Foster’s chance, and she has blown it.