Your school is a for-profit college but accredited by national organizations, so it is likely that the school has voluntarily adopted an internal administrative appeals process. Check with the Dean of Students or student handbook. The appeal process is likely to have very short time lines, so do your due diligence without delay. If the facts are as you say, the school administration may see fit to reverse the instructor's decision. If not, consider contacting the US Dept of Education and the agencies that have accredited your school with complaints. Let the school know that you will do that if the matter is not internally resolved.
In short, the instructor has the absolute right to limit the topics on which students may give an assigned "public speaking" presentation. But the instructor's remarks are highly suspect and it is unlikely that the school will want to defend those remarks against complaints to outside agencies -- assuming that the facts you recite can be proven.
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