So, let’s say such a train takes the same security as amtrack does, which is to say very little.
If the train is a viable option it would need to compete on time but there’s a caveat. The flight between the two cities is 2 and a half hours. Not including getting to the airport early, going through security, and waiting for your flight. So we can reasonably say it’s 4 and a half hours of down time.
The distance the train would travel is just over 700 miles. A 200 mile per hour bullet train at best possible speed does that in 4-5 hours. Assuming it’s express, and there are no delays.
If the train is faster and similar in cost it’s a no brainer, take the train every time. If it’s more expensive, which is will be if it isn’t subsidized, then it won’t succeed. People will see the longer travel time and not consider security and waiting around, and just buy the cheaper ticket. Then curse ass spirit air gets them stuck on the tarmac.