The whole 100W thing was, as far as I can tell, an almost completely unsupported theory advanced by a Mac blogger about why Apple doesn't put bigger batteries in their laptops. There is apparently some FAA document saying something to that effect, but of course there are lots of regulations on various books that are unenforced or unenforceable, and there have been dozens, maybe hundreds, of laptops made over the years with larger batteries, and none have ever been, to my knowledge, barred from flying.