I just found it odd that they would have a gun bath filled with gasoline inside a training room
I'm sure the author/reporter was simply mistaken. She was probably looking at a perfectly normal solvent cleaning station.
I can absolutely assure you that Army Special Forces garrison arms rooms, class rooms, and maintenance bays have been using standard auto shop/weapons parts washers (filled with solvent...not gasoline) for over 40 years. Any supervisor or leader who allowed a solvent tank or wash tray to be filled with gasoline would be fired on the spot for stupidity.
In a remote field location or combat outpost with no solvent? Sure. You do what you have to do...carefully.
As an SF sniper, I was taught a common technique to periodically clean the trigger assembly on glass-bedded M21 Sniper Rifles. We would carefully squirt that component with Zippo lighter fluid (Naptha), which would dissolve gunpowder residue and flush dirt, salt, moisture, or sand out the mechanism. The fluid would wash out the residue and drip downward towards the trigger guard...then evaporate. You couldn't pull out that assembly (as with a normal M-14) without ripping it out of (and ruining) the bedding job. Best done out doors.