Piecemeal rebellion
His rebellion had come in stages, bit by bit.
The Earthbreaker had actually been out collecting scandium three times prior, but that had been the first time he'd taken it out while a survey team was present in the area. He could have struck sooner and harder with his mechas- he knew the moment that Thunderbird Shadow had landed on his ship's back- but he remained the obedient leashed dog and waited to be told to attack, giving International Rescue time to get a good look at him and his systems.
When he'd snatched the safe from the Creighton-Ward house in Bay City, perhaps he could have been somewhat more stealthy with his Crab ship and much more careful with the safe- scanning it and researching its features instead of simply brute-forcing it open. But he'd been told to hurry, hadn't he? And that had meant a ham-handed approach.
In the theft of the TV21, he could have acted far sooner after Gordon rescued the two researchers who'd been stuck on board, instead waiting for them to be carried clear. When he overloaded the power plant and directed his ship to entangle itself with Thunderbird Three, he'd only done it because The Hood screamed inside his skull for him to do so, but he still telegraphed his actions as best as he could to give them a chance to escape.
The Antlion could have been ready three weeks earlier, but scheduled deliveries of the raw materials and the components he couldn't manufacture himself had been inexplicably disrupted and delayed. Couldn't be helped really, he had to be careful, the GDF and International Rescue were looking very hard for leads.
All that time he'd spent studying the ocular implant, how the control device worked and tested his theories on how to disrupt it. Interference from distance, his equipment, the masses of metal he was surrounded in with his machines, these all served to cover him while he laid his own plans to escape.
Plausible deniability had been his watch word as he carved out a little more freedom for himself bit by bit, laid his own plans and skimmed off resources and money into places The Hood would never think to look as he built his piecemeal rebellion.