They call Heiwa a crank.
Just possible because he is?
Why should I take a website devoted to putting down others as credible?
Maybe you should read it and find out?
Antimatter can get us to the Moon and back again.
Sure but we don't have more than a trace of antimatter as yet, though I've used a tiny bit.
And we don't need anti-matter to get people to the moon nor spacecraft anywhere in the solar system.
Even nuclear-powered rockets might do better than chemical rockets but people seem fussy about all that radioactive stuff spread around on a launch failure.
Long missions sometimes use nuclear "batteries" and at least one has crashed causing a bit of panic:
1968 Satellite Launch Failure Dropped Nuclear Batteries into Californian Waters.
Imagine the result is an anti-matter spacecraft crashed!
The tricky bit is not even in its production or storage. Those will be figured out long before its use in safely accelerating space craft.
Think of a motorbike accelerator. It's like twisting the handle a poofteenth of a mm and near instantly riding faster than a plane at full speed.
These fragile bags of water, bones and a few other chemicals, are what limits the acceleration of some manned space flights now.