Joel Davis, 30, appeared before Sydney magistrate Daniel Covington on Friday, when he was denied bail.
The National Socialist Network mouthpiece allegedly used a carriage service to encourage abuse and hate towards independent Wentworth MP Allegra Spender.
Davis is accused of calling on supporters to "rhetorically rape" the parliamentarian in an encrypted online platform after she condemned the group for holding a rally to "abolish the Jewish lobby" outside the NSW parliament earlier in November.
Representing Davis, Liam McKibbin told the online court hearing his client's pregnant partner was due to imminently give birth to their son.
The pair have planned a home birth with a midwife at their Bondi residence.
Noting the "alleged disturbing conduct," the defence lawyer said it doesn't include a "specific physical threat of violence".
Opposing bail, prosecutor Kristen Wakefield said Davis' South Australian criminal history showed he is bailed to an address there.
She said he was an unacceptable risk, noting failure to appear, danger posed to community safety, and the alleged offending occurring while on bail.
Ms Wakefield said due to Telegram's wide audience, it would be very difficult for federal police to conduct compliance checks to ensure he wasn't continuing to offend.
Refusing the bail application, Mr Covington said there was an unacceptable risk of Davis committing a serious offence and endangering community safety.
He will next appear before court online on December 3.
Australian Federal Police National Security Investigations teams have arrested three people, including Davis, in the past week for allegedly harassing or threatening parliamentarians.
They include a Tamworth man, 29, issued a court attendance notice for allegedly sending online threats to an Australian high office holder, in addition to a 32-year-old Victorian man for allegedly using a carriage service to harass a politician.
AFP acting Assistant Commissioner Matthew Gale said 951 referrals had been made in the 2024/2025 financial year over threats to federal politicians.
"The AFP is very concerned, and our national security investigations teams, alongside with our specialist protective command, are working hand in glove with our federal parliamentarians to make sure that we provide them with the assurances and the safety that are required," he told reporters in Canberra.
"Threats against federal parliamentarians is a significant issue for us."
He said there had been year-on-year increases in threats, with a 63 per cent rise over the last four years.
