so, i'll assume that you got this sentence from
here.
importantly, note that 'seat-sharing' is hyphenated in the original text, making it a single word; also, note that 'grabbing power' is followed by an essential modifier (grabbing power
for their benefit). individually, but especially taken together, these considerations mean that the two structures aren't going to be exactly parallel no matter what, so that the ostensible lack of parallelism you've cited is less of an issue.
if those words were to be non-hyphenated and taken alone, then i agree that your version is better.