The suspended leader, Md Akter Hossain, is also a teacher of the college who was seen in a video of the incident, during which Swapan was garlanded with shoes on Jun 18, the ruling party's Narail Sadar Upazila Unit said in a notice on Friday.
Akter was president of Bichhali Union Council Unit of the party.
Condemning the public shaming of Swapan, the notice said Akter failed to act as the unit president and he cannot evade responsibility for media reports on his presence at the scene.
According to locals, some Muslim students asked the Hindu student to delete the post on Jun 18 after he had gone to the college.
Tension mounted when rumours spread that Swapan took the Hindu student's side. Angry Muslim locals and students set the motorcycles of the principal and two teachers on fire. The mob also clashed with the police.
A video of the incident showed the locals and students putting a garland of shoes around Swapan's neck in the presence of police, accusing him of belittling Islam for his alleged attempt to save the Hindu student from the same mob.
The law enforcers took the principal along with the student to the police station. However, police said the principal was not detained.
The Bangladesh Directorate of Secondary and Higher Education has formed a committee to investigate the incident amid protests across the country.
Swapan has not been staying at home since the incident. His wife said he went into hiding because he was feeling insecure.
Police started a case 10 days after the incident and arrested four suspects amid nationwide protests and condemnation.