Good map, however, it's relatively easy to get to the inhibitor.
Spoiler
A single mortar in the first PZ + 2 sprayers near the inhibitor can already clear the area for a nullifier, even without fire rate/range upgrades.
I managed to destroy the inhibitor at around 5 min, the rest of time was required to collect the key, the message and to re-convert that flip-mitter.
But anyways, well done!
While I'm not as good as Tyler I accidentally did something like him.
Spoiler
I put a mortar on the first PZ just to keep the creep down while I went to the SE island. After taking the SE island I noticed the mortar (with upgrades at this point) was keeping the creep around the inhibitor to near zero. I dropped a few sprayers onto the center, they cleared a patch for a relay. Then it was just collecting the key and message capsule.