Canapino, its 34-year-old Argentine driver, was at the center of controversy this week with his actions on social media that included a statement which rejected claims that his supporters had threatened rivals.
Arrow McLaren's Theo Pourchaire drew the ire of Canapino's fans after colliding with him in last weekend's Detroit Grand Prix. Pourchaire then flagged the abuse he'd received on his social media channels, which led to more online hate being thrown his way.
The situation led to the termination of Arrow McLaren and JHR's strategic alliance on Thursday, which originally formed last October.
Canapino will now be "taking a leave of absence" for this weekend's round on the 4.014-mile road course. He will be replaced by Siegel, a full-timer in Indy NXT who failed to qualify for the Indy 500 after a wreck while making a last-gasp bid to make the field.
"The growth of online abuse and harassment resulting from the events of this week have led to a very difficult experience for Agustin, the team and the entire IndyCar fan base, and the safety of Agustin and the rest of the competitors has to be considered first and foremost," a press release from the team said.
"Abuse, hatred, and harassment in any form is a detriment to this sport, and we must prioritize the mental and physical wellbeing of both our drivers and our competition."
Brad Hollinger, JHR's co-owner, stated: "Online abuse is unacceptable, and we need to ensure that our drivers are prepared both mentally and physically when they get in the car," said.
"We are saddened by the events that led to this scenario."
It is not known at this time if Canapino will return for the following round at Laguna Seca.
The release also stressed that "Juncos Hollinger Racing is working directly with IndyCar to create a better community for our fans, drivers and team members, uniting to make IndyCar a welcome sport for all."
Canapino's replacement Siegel has made one points-paying start in the IndyCar Series (Long Beach, 20th), and also competed in the non-points exhibition at The Thermal Club.
Both starts have come with Dale Coyne Racing, with his only other scheduled event with that team being Toronto in July.