As long as everything was recreated, and not one bit of the original is used, you could win with the right lawyer (I think, IANAL)
Plus I think clean room process needs two separate teams and this is just one guy.
I did find this post from actual lawyers about it, but basically it's a grey area that hasn't been decided yet.
https://www.beankinney.com/news-and-insights/blogs/512000-li...