[3] Now one Alcimus, who had been chief priest, but had wilfully defiled himself in the time of mingling with the heathens, seeing that there was no safety for him, nor access to the altar,

Notes:
[3] "Alcimus, who had been chief priest": This Alcimus was of the stock of Aaron, but for his apostasy here mentioned was incapable of the high priesthood, but king Antiochus Eupator appointed him in place of the high priest, (see above, 1 Mac. chap. 7., ver. 9,) as Menelaus had been before him, set up by Antiochus (above chap. 4.), yet neither of them were truly high priests; for the true high priesthood was amongst the Machabees, who were also of the stock of Aaron, and had strictly held their religion, and were ordained according to the rites commanded in the law of Moses.-- Ibid.

[3] "Mingling": with the heathens; that is, in their idolatrous worship.

That's how Catholics should view modernist Novus Ordo clergy even those clergy who think it is more important to be in communion with the Novus Ordo sect than to it is to speak the truth about heretic clergy.  Judas Machabeus certainly didn't think he was compelled to recognize Alcimus as high priest.  Rather he took up arms against the kings who promoted Alcimus.