Using sodium polyacrylate to clean flooded homes
It is safe enough to use in baby diapers, so from a people perspective, it's safe to be in contact with it.  

It is added as an amendment to soil to get the soil to hold more water for plants.  So if you use it inside a house and dump it outside, you could mix it into the soil.  

One of the videos mentions adding iodine to the sludge to turn it back into a liquid.  It isn't clear how much iodine you need, or what iodine would do to the soil, but it is used as a disinfectant.  So in a flood situation, iodine in small amounts would probably be helpful.

The issues you raised:


Slippery floors: You need some way to get the water out.  If you have a pump or vet vac (or buckets), you can get the water out as water.  Otherwise, getting it into more solid form probably makes the job easier.  Once it's down to just a slippery film, you would need to clean that up.  You might be able to mop it, or sprinkle on the kind of powder used to absorb and sweep up spills commercially (various materials; a common one is a mixture of sawdust and ground corn cobs).  That's a standard janitorial supply item, and may even be available at hardware stores.  You could also try just wiping it up with rags.  

As long as you're aware that the floors will be slippery and take care not to slip and break your face, slippery floors would seem like a minor problem compared to the water,
Ditches: Mud will flow into ditches in a flood.  I would think the powder would reduce the amount of mud flowing into ditches.  Regardless, the powder shouldn't significantly change that problem or the remediation.
Sewers: Mud will flow into sewers in a flood.  It's possible that a lot of the powder mixed with mud could change its flow characteristics inside the sewer and perhaps be more likely to cause blockages.  However, remediation would be the same as for mud, alone.  It would take a freaking lot of the powder to significantly change the mud washing into sewers in a flood.


I think the concern with ditches and sewers is from using massive amounts of the powder outside to stabilize mud flows.  Using it inside the house and then disposing of it responsibly (e.g., mixing it into the soil or hauling it somewhere), shouldn't adversely affect ditches and sewers.