The abuser did not show up for the order of protection hearing. Can his/her guns still be taken away?
Maybe. The abuser does not have to come to the hearing in order for the law to apply to him/her, but s/he does have to be given notice of the hearing and an opportunity to attend.1
If no hearing is scheduled, and/or no notice is given to the abuser about the court hearing, then the federal firearm law might not apply to your abuser.2
1 18 USC §922(g)(8); See, for example, United States v. Bunnell, 106 F. Supp. 2d 60 (D. Me. 2000), aff'd 280 F. 3d 46 (1st Cir. 2002)
2 See, for example, United States v. Spruill, 292 F. 3d 207 (5th Cir. 2002)