I don't think it is a problem to get plants established after soil floc but you may have to plant them yourself. The soil floc layer can't be more than the top 1 or 2" and you can easily penetrate with a shovel. If you plan to add 'desirable' plants I see no issues.

I may be wrong about the soilfloc acting as a barrier for seeds to establish on their own. It is hard to do a truly scientific study on that. First, not many people get to put soilfloc in a pond that is brand new with a bare bottom. I was able to do that only because I had just prior to soilfloc done a complete plant kill and had added crayfish. Plus the goldfish and crayfish (probably the crayfish) were stirring up the bottom and I had like 3" visibility that whole summer so no plant life. I then did the soilfloc in the fall so basically treated a bare bottom pond.

Most people add it in a pond that already has vegetation so probably always have places where the bottom stays 'mucky' and where plants can grow, spread, new seeds can root etc.

Others can share if they had new vegetation coming in places where it wasn't before after soilfloc.

Also, the seeds for aquatic plants often come from ducks, geese and so far we have had very few visitors so maybe my pond will grow weeds like crazy once the seeds actually arrive in the pond?

For now I'm happy since the weeds that did grow in the past were unwanted invasives (eurasian water milfoil) so at least if I want to get some hardy lilies or other desirable pond plant going, I can control how many and where I want them!

As for walking on it, it really isn't slippery. It feels more like walking on a crust, not a bad feeling. But once I get in a little deeper water (where I haven't been as faithful about raking out the leaves) everything feels kind of squishy and nasty like you would expect a pond bottom to be when things decompose and settle.