This is just a variation on the fish oil method, but it's a delaying tactic only not to mention very difficult to actually do with things like that R34 strut reinforcing plate. If you wanted to go down that path, you'd be better off using a an inhibited corrosion wax like this:
https://ppcco.com.au/bilt03.html
This is the aerosol version designed for cavities but I think also available as brush on.
These are mass produced unitary steel body cars.....rust is inevitable without integrated corrosion protection. Some manufacturers moved to zinc plated panels in some situations, but that's expensive and very uncommon when these cars were made and even now. The move to thinner HSLA steel sections (lighter cars) didn't help.
The R34 strut corrosion problem is caused by the fact that they included a reinforcing plate (probably because of the width of the tower) without decent corrosion protection for the cavity between the plates. Corrosion was inevitable, just a matter of when it appeared. Short of zinc plating the sections, inhibited primers and wet-setting (inhibited sealer) would be the way to go (as in aircraft) but never going to happen on these sorts of cars in production.
The only way to treaty the R34 issue is to do what some people are already doing - remove the plate, remove the rust, treat the area (phosphoric acid based converters only please), weld if necessary, prime, seal, etc, etc. Personally I would zinc plate or even galvanise the re-inforcing plate before putting it back and, of course, weld-through primers.
R32's have a different strut tower design so don't suffer the same problems, but there are still overlap welds so may well do so in extreme situations - eg salted roads. Having just done a lot of rust repairs on my R32, believe me, they definitely have their own problem areas - sills, rear-wheel arches, etc
Christ, I'm back to lecturing (shudder....).