This sorta suprises me. I would think they would think this was good for their business. Regardless of if someone uses their messenger program or not, they still have to get users to sign up for their service. Although their already huge, the bigger you get, the more willing advertisements and things come into play and make their business even more valuable.
If i was starting a company, no telling how much I would pay for trillian to support my services knowing that thousands of people use it and it would be good advertisement and make it more appealing to register for the service to incorporate it in their 'List O'Messenger Systems'.