DY – I know you meant it derech s’chok but it’s not cute, or even a proof for two reasons:
a) The rhyming supposition is unfounded, as the words “shabbos” and “sorosecha” definitely do not and will never rhyme with “chelko[y]”
b)The two siddurim generally held to be grammatically most accurate (and those most widespread in the Germanic kehillos for the last 250 years) – siddur Sfas Emes and siddur Avodas Yisroel – both have “Sinai” with a patach and not a komatz in sight.