Not sure why you blame Baha'i for the obvious warnings given in all scriptures, Here is one given 2000 years ago
Matthew 7:15
15 Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.
That is just saying that they will take you away from the flock, take you away from the intent of God's Word.
So one has a duty to provide accurate information.
Baha'u'llah offered.
"Whoso layeth claim to a Revelation direct from God, ere the expiration of a full thousand years, such a man is assuredly a lying impostor. We pray God that He may graciously assist him to retract and repudiate such claim. Should he repent, God will, no doubt, forgive him. If, however, he persisteth in his error, God will, assuredly, send down one who will deal mercilessly with him. Terrible, indeed, is God in punishing! Whosoever interpreteth this verse otherwise than its obvious meaning is deprived of the Spirit of God and of His mercy which encompasseth all created things. Fear God, and follow not your idle fancies. Nay, rather follow the bidding of your Lord, the Almighty, the All-Wise."
Mirza Ghulam Ahmad declaration was after the Bab and Baha'u'llah. Mirza Ghulam Ahmad was taught the faith of the Bab and Baha'u'llah. Mirza Ghulam Ahmad was challenged on the fact that he was eclipsed by the Bab and Baha'u'llah, he never responded to thay challenge.
Thus we only provide information to enable people to make their own informed decisions.
You and all get to choose.
Regards Tony