I disagree. Just use caution when disassembling and reassembling to avoid scratching the ring or cylinder.
There is no reason the ring will not seat just as well after doing so. Use lots of oil when putting it back together. I am not aware of any way to hone the smaller cylinders anyway. If it's scored, buy a new sleeve and ring (piston too, if it's messy).
I do question why you would really need to disassemble to clean out varnish. If the whole engine is gummed up from sitting and won't free up with some solvent, only then I can see taking it apart. If it moves freely and runs fine, don't mess with it.