The MSDS for Stan's sealant shows no ammonia. It lists latex, propylene glycol and water. Any traces of ammonia would be related to the latex, which is also present in liquid frisket or masking material used by watercolorists. Ammonia acts as a sort of anti-coagulant with liquid latex, not a solvent. The ammonia evaporates in contact with air, and the latex dries and does its thing.
Ammonia is also present in many inks and is a common solvent for cleaning inks from pen nibs -- I've used household ammonia to clean years-old dried ink from calligraphy and art pens and nibs. It's been used for centuries on parchment, vellum and paper and the trace amount of ammonia has never been considered a risk to archival properties.
Stan's addresses concerns about ammonia on
its FAQ, and I'd be inclined to agree with their assurance that any oxidation, corrosion or rust are more likely due to the normally rough environmental conditions to which bicycle wheels are routinely exposed. Water, salts, limestone dust, etc., are all more likely culprits.
There may be traces of formaldehyde in some latex, also unlikely to cause oxidation.