The actual wording of the quoted regulation is:
"(d) Gravity or syphon feed prohibited. A fuel system must not supply fuel by gravity or syphon feed directly to the carburetor or injector."
So, my system, with gravity feed through a solenoid controlled valve and a roll-over valve to the fuel filler neck is NOT illegal.
Here's a link to the actual document, not a partial quote from a third party:
https://www.ecfr.gov/cgi-bin/retrieveECFR?gp=1&ty=HTML&h=L&mc=true&=PART&n=pt49.5.393#sp49.5.393.e
And, while I'm at it, regarding another quote from the ATTA website, environmental "whackos" are what saved us from disasters such as the Love canal, unbreathable air in our cities, DDT being sprayed indiscriminately around the entire world and other threats to life perpetrated by corporate greed and irresponsibility.