They aren't immune to engine damage, are they? I'll have to check. If not, getting a bunch of Riots on them might be worthwhile.
Two things:
1) They have 100K engine damage. Even for a riot, that will take a long while to bring down to a meaningful level
2) Enclaves are both faster and have a greater auto-kite range then riots, meaning they won't get close enough to attack at all.
Other guardians with a similar effective range to enclave guardians have speeds in the 40's instead of the 60's. The only exception I found was the implosion guardian, but that doesn't auto kite.