Should he KEEP doing stuff with them? Probably not. Maybe Twiztid, because those guys are crazy talented, but ICP? Nah. He's beaten that into the ground: any of ICP's fans that are gonna like him already do. ICP has a limited fanbase and they all KNOW about Tech N9ne now due to his work with ICP. Some like him, some don't, but ICP isn't gaining any new fans, therefore, Tech won't gain any new fans by working with them. So career-wise, there's really no benefit.
However, working with them in the past was DEFINITELY a benefit...most of you might not like them, and for good reason...but truth be told, "juggalos" are packing Tech's concerts, they're buying merch, they'll buy the new album, and they're really supporting him. He has nothing left to gain from future work with ICP, but he gained a LOT due to what he's already done with them. Yours or my opinion on ICP and juggalos is irrelevant: careerwise, it was a big boost for his underground-popularity that he didn't have before.
The other thing you gotta realize is...Tech wants to do it, so this is irrelevant. Tech and ICP and them are good friends. Tech is remixing an ICP song for their new album. He's performing a show with them on Halloween. He WANTS to keep working with them and he's name-dropped "juggalo" in his recent music. He likes the scene and he apparently likes the people, so....it'll probably continue.