I'm sure any company wishing to buy it from the registered owner would need to up that $2500 by at least a zero or two.
The next question to ask is, why should it bother a company so much that a companyname.sucks domain name exists that is not under their control? (i.e. why would they feel the need to spend $2500 or more to obtain it?)
It's pretty apparent that anyone who spontaneously types that domain name into their web browser probably already feels that (companyname) sucks, otherwise they wouldn't have typed in that domain name.
The other way people would find that domain name is by entering "companyname sucks" into a search engine -- in which case they will see all the "companyname sucks" pages, regardless of where they are hosted.
It's doubtful anyone is going to mistake such a domain name for a legitimate company-owned site.
And finally, paying the $2500 is definitely not going to prevent people from saying that "companyname sucks" -- they'll just say it on some other web page, and that web page's URL will be the one that comes up when you google that phrase rather than companyname.sucks. Six of one, half a dozen of the other, AFAICT.
I'd say that if companyname.sucks is getting a lot of traffic, that (company) might want to figure out why people think they suck and take corrective action, rather than simply trying to quash peoples' complaints.