From the article:
In February, NYPD's deputy commissioner for legal matters, Andrew Schaffer, told reporters that detectives can operate outside New York because they aren't conducting official police duties. "They're not acting as police officers in other jurisdictions," Schaffer said.
and
And New Jersey Attorney General Jeffrey Chiesa has said he's seen no evidence that the NYPD's efforts violated his state's laws.
If those officers-not-doing-policework were getting paid off the NYPD payroll while ‘not doing policework’ - they were doing police work, especially since what they found would be reported to the NYPD and used for their investigations. No different than any other stakeout. Legally parsing all they want changes nothing.
Personally if my SWAT team had found any of them there, I’d have busted their skulls open with a rifle butt, taken all their stuff, killed their dog, burnt everything else, and thrown them in the klink for some Bubba love, then busted their skulls open again for good measure.
BS. If they were getting paid by the PD for their time and efforts there, they were conducting official police duties.