Fucoidan: is it healthy?

I was looking at these supplements for glycocalyx and arterial/vein health, Arterosil and Endocalcyx Pro, and both of them contain seaweed extract, specifically Endocalyx Pro has Fucoidan.

Fucoidan is available by itself from Life Extension, Dr.s Best, and others.

But then I saw this post:

https://www.reddit.com/r/Supplements/comments/6n7guo/comment/dk7c3pe/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

They says it's "a bad thing." What does that mean?

"Fucoidan inhibits the formation of new vessels by which tumor cells receive their oxygen and required nutrients. Fucoidan has been found to inhibit the binding of VEGF, a key angiogenesis promoting molecule, to its cell membrane receptor"