I wouldn't want one micron of brake-fluid in my fuel-tank, no matter how diluted and filtered.
That is exactly why I refuse to use engine oil from shops, garages, and the like; those guys will pour anything in there, on top of Tom, ****, and Harry bringing all kinds of crap from home and dumping it in the barrel.
I see everything from old anti-freeze to dirty diapers dumped in with used oil, none of which I want in my fuel system.
Honestly, were it my truck, I would drain the tank, flush it out, steam-clean the insides, and not pour that stuff back in; fuel is high, but not that high.