Hobo wrote:

Were the Have Blue and Tacit Blue codenames arbitrary constructions or
was there some sort of logic behind them?

The names (officially called "nicknames") are essentially arbitrary.
However, the first words ("Have" and "Tacit") are not completely
random, because the first two letters must come from a defined subset
allocated to the DOD component or agency, which supervises the program.
The second word can essentially be chosen at will, and in the case of
classified programs is selected to have no connection to the nature of
the program (which is definitely the case for "Blue"). The second word
of open programs is often related to the program, e.g. the conversion
of F-106s to QF-106 drones was made under the name "Pacer Six".

Andreas