Yes it seems to have infinite energy but the throughput is limited to 2g of acceleration, unless you give it infinite time as well it will not reach c, though it would approach it.
Doing some calculation the final speed of 33kg, falling in 2g, for 70 years, without friction is “only” 99.77% the speed of light.
Edit: Forgot to convert the 0.9977c to percent.
It doesn’t though? IANAL but as far as I can tell you can fork, modify and redistribute it as long as you provide the source code to your users.
It’s AGPL-3.0 so… https://www.tldrlegal.com/license/gnu-affero-general-public-license-v3-agpl-3-0