There is no ground rule that "forces you" to implicate yourself as person as committed to the positions you take as debater. But there's also no ground rule that prevents your opponent from trying to implicate you in that way. If they do, you get to choose how to respond. In general what it means to "play by the rules" has always been up for contestation in competitive policy debate (see also "topicality" arguments and arguments about what one is entitled to "fiat" as part of one's proposal). If one wants to win under a certain conception of the rules, one also needs to be prepared to defend that conception of the rules. In another version of debate that might not be true - perhaps that's "public forum", which I know little about? - but for many policy debaters I think the fact that everything is open to question is part of the challenge and the fun.