I didn't have my comparison backwards.
https://www.machinedesign.com/materi...d-other-metals
Of the five materials, 440C stainless steel has the highest specific strength, followed by 4130 alloy steel, 7075-T6 aluminum, and 2024-T3 aluminum. AISI 304 stainless steel has the lowest strength-to-weight ratio of the five.
For both UTS and 2% yield strength, 440C stainless shines over the other steel and aluminum alloys in this comparison. 4130 alloy steel comes in a close second. Aluminums fall at the bottom in terms of UTS, but 304 stainless steel has the lowest 2% yield strength at 42.1 ksi.
Shear strength, the maximum stress a material endures before it fractures, comes into play when components see off-axis forces. Shear strengths are not typically quoted for stainless steels because they are too low to have engineering value. 4130 alloy steel has shear modulus around 11,000 ksi, lower than those for the aluminum alloys.
Another problem with stainless steel is galling. This typically takes place when stainless-steel fasteners are highly torqued, marring the material’s passivating oxide surface film.
Grade 303 is a tad 'worser' - the difference with 304 is sacrificial (strength / corrosion resistence) in order to allow easier machining.
Stainless and aluminium don't corrode "eachother", nothing happens to the stainless side of the galvanic corrosion - it's just the aluminium that dissolves to white powder, so it can ruin aluminium frame / crank mounting holes. A very common example: take out an inner tube - it has a stainless steel valve that goes through a hole in an aluminium rim. See the white dust on the valves thread. That's alu from the rim - the hole got bigger.
My current bike stand was mounted along 2 grade 304 (A2-70) bolts+nuts, through an aluminium block between the frame tube and the stand. My stand kept on losing, until the point I had to retension it several times in an hour when having parked alot. The holes in the alu block and the stainless bolts hung full of white powder. Just to say - it's something to take into account, in an aluminium bicycle frame/part and all weather case. Thread in the frame can get damaged meaning a loss of mount points.
Electro polishing is just irrelevant to galvanic corrosion.