Technically, it's illegal to own a trademark-TM-domain per se, so the real questions are:
1) Does forwarding show "bad faith", otherwise increasing liability?
Forwarding to any site other than the intended site is in bad faith.
2) Is forwarding preferred to parking in a legal sense?
In either case, you are capitalizing on traffic that was intended for another firm; thus, both uses of traffic can leave you liable.