I think there may be problems with some of the proposed ideas such as the EA taking out mortgages. I don't think that this can be done by government departments.
What could be done however is a sale and leaseback. The EA could sell the houses and then lease them back from the purchasers. This would raise capital and keep availability for lock keepers. If there are lock houses that are genuinely surplus away from the locks then maybe there is an argument for selling them however it look like there would need to be some arrangement to compensate lock keepers if they need to rent as salaries seem very low.
Overall it looks like a DEFRA-forced capital raising exercise may just be being handled poorly.