It would have been known locally that the people in the Drogheda IPAS centre were women and children, whoever did it didn't care, and was prepared to kill women and children to further their terrorising agenda.
The 'we don't want unvetted males' line is weak because there have been objections to women as well - I remember in 2019 a small number of women from Syria - I think it was about 12 - were due to be temporarily housed in Achill Island for a period of rest and recovery from the war in Syria. The locals were so angry that the women had to go elsewhere.
It is normal for emigrants to be younger men going overseas to try and set up a new life for themselves and their families.
That's how I have English and American cousins
And it is young men of military age who are being press-ganged into fighting in various conflicts, 'kill or be killed', so it's not surprising that parents would do anything they could to get their sons beyond the clutches of whatever murderous group wants to recruit them.
There are at least two IPAS centres not far from where I live, and not a bit of trouble. I know of towns and villages that rallied around to do whatever they could to make the newcomers welcome in their area. It's not inevitable that IPAS centre=trouble.
If there is is a centre full of young men, wouldn't it be great if the young men of the local area made contact, brought along a football for a kick-around, helped with English classes, and showed by example how to be respectful towards Irish women and children. Because Irish men have so much to teach foreigners about being respectful towards Irish women and children, haven't they??