I think he means using extra pieces that aren't parts of the original robots in order to combine them. To be honest, I don't like that, either.
Not a single piece of the combined mode isn't capable of being part of the normal robots while separate. The fists, feet, connector pieces, leg armatures and even the pieces that fill in Dead End's arm mode are all made out of pieces of Motormaster's trailer, all of which can plug into Motormaster himself in robot mode, and all of which is neatly contained in his trailer in vehicle mode. In fact, the only time there are extra pieces in any configuration is when they're combined. There are two parts leftover after you combine everything, which are the two arms' small guns, although they can be plugged into numerous pegs on Menasor if you just want to keep them in place, which makes the combined mode completely self-contained.
Partially yea, seems like lot of stuff you have to pop out to get it to stick, also stuff like the legs not actually being the combiners, but simply the cars that clip onto the leg/feet parts.
I don't really know what you mean by stuff you have to pop out to get it to stick. The legs are ingeniously designed, and the use of an armature for the cars to plug into results in thicker, better proportioned legs and a closer resemblance to the G1 animation model. It also allows the limbs' car modes to remain intact, as they're frankly too small to fit a plug large enough to connect to the torso properly. It's also nice to see a combiner that tries some new tricks rather than the usual stuff, and in fact the "plug-and-lock" system the combiner limb pieces use to connect onto Motormaster are very clever and will hopefully be used/stolen for other third party combiners in the future.
It takes some time to figure out, no doubt there (my first time combining them took about an hour), but they're all solid in all three modes, they look fantastic in all three modes, and Menasor holds together and poses better than any other third party combiner I have. Out of TFC Hercules, Maketoys Green Giant, and TFC Uranos, I have to give FP Intimidator the nod for #1 (MMC Feral Rex may take that spot soon, though). He's smaller than the others, but this is the Stunticon team I always wanted but never thought I'd get. If you like the Stunticons at all, I give them the highest recommendation.