Civil asset forfeiture should not be considered constitutional, and some day a test case will make it to the SCOTUS. As for this case though... the pardon does not make Ulbritch innocent! On the contrary, accepting the pardon implies guilt. So the pardon need not and might not extend to forfeitures. Though it's also possible that the presidential pardon could extend to the forfeitures, but I suspect that's a constitutional grey area.
Civil asset forfeiture connected to an actual crime should be. You should not own the guns you used to murder someone else, e.g.
Otherwise it's "your $100,000 in dollars in cash looks guilty to me."
Cases have made it to the Supreme Court --- recently! --- and it held up just fine. This is another message board fixation. I'm sure it's abused all over the place. It wasn't in this case.