It doesn't sound like he supports forfeiture in general. According to the article "And Justice Clarence Thomas (the lone dissenter in the Nelson decision) recently slammed civil forfeiture for its “egregious and well-chronicled abuses.”"
Generally when the question "who the heck dissented on that?!?!" is asked, the answer is Thomas.
That's because he interprets the Constitution and the law according to what he believes them to mean, not according to what he wishes they would mean.
In this case, he clearly states that he sees no constitutional requirement for the State to return property after it has been confiscated post-conviction (as an aside, the article title is misleading: this wasn't confiscation prior to or absent a conviction). The Constitution does not mandate all good things, nor does it forbid all bad things.
The constitution does not mandate all good things, does not forbid all bad things, but VERY NOTABLY includes the 9th amendment. They put that one in for a reason.