No. The particular manga at issue might have been judged obscene, had the case gone to trial. But it did not go to trial, and even if it had, unless it had been appealed, and the appeal upheld the conviction, it still would establish no precedent.
Not much of a distinction, but it IS an important distinction. Nobody (for example) is going to be prosecuted for Negima!, even considering it’s crammed full of lolicon. There’s a line, and even though it’s pushing that line real hard, it isn’t even close to the edge.