I just did a quick test with quarto, which uses pandoc markdown and pandoc for conversions, and it looks like pandoc doesn't recognize #nospace as a header (although this could be a quarto specific thing).
A quick look at the python library op is using and it seems that that is what they are using to convert to html, rather than pandoc.
that's the problem. The license is only good in spirit, and simply doesn't work in practice.
For example, a corporation could run a subsidiary business which doesn't make enough money to violate the license, which then rents use of the software to the the big corporation. Google used to use a similar scheme, to shift money around and essentially evade taxes.
Although in a legal system where money is a win button, you can't really win going to win even if they just decided to violate the license.
Anyway, if you don't want big corporations to use it, just use the AGPL.
Google basically bans use of the AGPL internally — you can't even install AGPL apps!