I think the only thing making it NOT legal is the shortness of the front 2 stubs. The inner slants I don't think count as bumpers because they are not "the outer-most set of exterior vertices", they are just extra safety for the field.
Least I hope thats the only reason. We at 1745 have a very similar frame( but our short stubs are greater than 6".
As for the GDC making a ruling on this. I personal do think this will happen( not that I have inside information . . cause I don't). but mainly because figure 8-2 has an angled frame and it shows the line to follow the angles( granted they are outward angles) . . that picture does kinda muck things up and you know what they say about pictures vs words.