The entirety of the Hermit's declaration isn't posted in the OP, nor is it posted on the "Complicit Clergy" blog, though there is a link to the entire declaration on the Complicit Clergy blog.
There are at least two more paragraph's to the declaration, which I suspect is what got them into trouble. Here's a part of the last two paragraphs:
"We who are watchmen of the Church, who must speak from the watch tower of Truth, have no option but to withdraw our obedience from Pope Francis and sever communication with the Holy See (xxi). We do this with great fear and trepidation, but we cannot take part in the Pope's sin. This is not an act of schism, nor is it an act of defiance, it is an act of real prudence...."
https://choosing-him.blogspot.com/2019/12/scottish-hermits-critical-of-francis.htmlI found the above link on the Catholic Truth blog in Scotland, and the owner of said blog is an adherent of the SSPX, and she is critical of the Hermit's stance. Maybe she believes that the Hermits are sedevacantists. But I think not, since they do refer to Francis as "Pope Francis."
I find it interesting that Bishop McKee is the one who has excommunicated the hermits, since he is not the ordinary for the Orkney Islands. The ordinary for Orkney is Bishop Hugh Gilbert. Bishop Gilbert has been known to be sympathetic somewhat to tradition (a rarity in Scotland); not sure why he was not involved in their hermit's excommunication.