JK you are CORRECT.
the 2 different fluids won't cause each other to gel.
the 2 different fluids won't mix with each other also.
they also have a slightly different compression rate so mixing A LOT of the 2 fluids together can give you troubles.

i have replaced regular brake fluid with silicone on a LOT of old vintage cars without flushing anything. i just remove as much fluid from the master as i can. them pour the DOT 5 in. now bleed the brakes until you see the DOT 5 come out of the bleeders.the DOT 5 will push most of the old fluid out of the system without giving you any troubles. after doing this to all 4 wheels i start over and bleed another cup or more of fluid from each wheel just to make sure the old stuff is out. i also like to tap on the brake lines to get any small air bubbles out that like to hide in sharp bends of the brake lines.

keep in mind DOT 5 brake fluid RETAINS AIR just like the old fluid does water. this is why you can't use it on ABS cars.
i also like to heat up the new DOT 5 in a pan of hot water to force any air mixed into the fluid when it sits on the shelf or shaken up during shipping.some installers don't do this and can never gets the brakes bled properly. this is why DOT 5 brake fluid gets such a bad rap.


DO A SEARCH on DOT 5 brake fluid. this subject popped up a lot in the past so there are multiple threads with the exact same info already here.