Was there ever such a thing as a “temp” security guard brought in from some other police field?
I've never heard of it happening, especially when the people brought in, weren't even actual Secret Service agents, but TSA agents. That's crossing over into a totally different agency. That's like taking a Border Patrol Officer and sticking them in an airport for a day or two, processing travelers. It would be a breach of security. The other thing is that it may violate Federal law, Civil Service Law, and/or Federal Labor Law.
I worked in NY State Corrections. There's no way that any other uniformed State employee such as a member of Park Police, Campus Police, or State Police would be allowed to cross-over and work in another agency's slot, even temporarily. I was a Peace Officer. They are all Police Officers. I could carry a weapon on the job, and off, purchase weapons on my badge. I had to qualify each year on the weapons the agency used in order to keep my Peace Officer status. When I retired, it ended.
I also found through a search that the majority of TSA officers are security officers, not police officers. They have no arrest authority and can't carry weapons, but there are some who are law enforcement officers, and can and do carry a weapon on their job. That still doesn't mean they can be pulled from one agency, and used in another. It never happens.