All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
To answer this question we would like to make the following points clear: First, this scholar reported a Hadeeth (narration) in the mosque and this is lawful according to the four Imaams: Abu Haneefah, Maalik, Ash-Shaafi'i and Ahmad all. Thus, he should not be punished for narrating a Hadeeth. In fact, his narration of this Hadeeth does not necessarily mean that he believes in what he says. So, judging him for narrating a Hadeeth is void and illegal.
Second, the Hadeeth he reported is a sound Hadeeth reported by Imaam Muslim from Anas who said, "A person said to the Prophet, 'O Messenger of Allaah, where is my father?' He said: '(He) is in the Fire.' When he turned away, he (the Prophet ) called him and said: 'Verily my father and your father are in the Fire.'"
The scholars differ over the issue of the fate of the Prophet's, sallallaahu ‘alayhi wa sallam, parents. Some of them said, "Only Allaah knows what awaits them as it is only Allaah who knows what they did." Thus, one should not describe them as Muslims or as disbelievers because they did not hear about any prophet and no prophet came to them. Therefore, they are among the people who will be tested on the Last Day and as a result their destiny will be decided. Other scholars said that the Prophet's, sallallaahu ‘alayhi wa sallam, parents became Muslim. They base this opinion on some false Hadeeth that state that Allaah The Almighty revived the Prophet's, sallallaahu ‘alayhi wa sallam, parents for some time so that the Prophet called them to Islam and they became Muslims. However, this opinion is totally wrong because it is not backed by sound evidence.
A third group of scholars said that the Prophet's, sallallaahu ‘alayhi wa sallam, parents were disbelievers basing their opinion on the sound Hadeeth narrated by Imaam Muslim (see above): They said, commenting on this Hadeeth, "This does not imply any defamation of the Prophet himself, because it is learned from the sound Hadeeth.” An-Nawawi said, while interpreting this Hadeeth: "Whoever died while he was a disbeliever, he will be in Hell-Fire on the Day of Judgement no matter how close he was to pious and good people." He also deduced from this Hadeeth that the Arabs who died in the pre-Islamic era while they were worshipping idols would have the same fate as the disbelievers.
This does not mean that those would be judged for something they did not know. In fact, the call of Prophet Ibraaheem to Islam and of other prophets did reach them. Imaam An-Nawawi also added that the words of the Prophet saying: "Both my father and yours are in Hell-Fire" is a sort of good behavior towards this man. It is as if the Prophet was telling him that both of them are afflicted by the same distress.
Allaah Knows best.