Udrp outcomes?

we've had a customer who'd been trading as abc xyz xyz private limited for decades. they'd been using abcxx.com for years. but they forgot to renew at one point and a..cybersquatting firm? squatted on it. the last 5 years, this customer used abcxx.org and abcxx.net variously; the firm that owned the domain also offered it for sale, including to our customer. however, recently our customer finally started to reclaim abcxx.com via the udrp(although its a .com and the current owner of the domain is american, the arbitrator is in hong kong..maybe because our customer is singaporean). thing is, now the other side(after offering a reduced price from what they were previously asking for) is offering 'amicable settlement' -> handing the domain back free of charge. whats the catch? should we finish with the udrp process or should we take the offer up? why are they eager not to follow through with the udrp? in fact, in their offers, there's been a vague threat of having to take other legal actions to counter our actions.. what could they be?