[EricH]

Here is the entire rule that includes the compressor Spike allowance:

[R58]
The control system is designed to allow wireless control of the Robots. The Driver Station software, FirstTouch I/O module, cRIO, speed controllers, relay modules, wireless bridge, and batteries shall not be tampered with, modified, or adjusted in any way (tampering includes drilling, cutting, machining, gluing, rewiring, disassembling, etc.), with the
following exceptions:
[...]
E. The fuse on a relay feeding the compressor may be replaced with a 20 Amp Snap-Action circuit breaker (recommended).
[...]
M. Devices may be repaired, provided the performance and specifications of the component after the repair are identical to those before the repair.

(emphasis mine)

By replacing the fuse in a Spike with a breaker, you are modifying the performance (it will continue to function after an overcurrent event, which it probably would not with a fuse). While this probably won't harm the Spike, and the Spike is already supposed to be protected by a 20A breaker on the PDB, it is nonetheless a modification. The reason that it's allowed for the compressor is that the compressor draws a large startup current, which tends to blow the Spike fuses; having the breaker allows the compressor to keep running.

Short version, I'd call it illegal except on the compressor Spike; this is the safe call. (You could make the argument that it's legal on every Spike, but you'd probably be pressed to hold that position.)