Yes, there is a valid reason - market share wars
Without evidence its not really worthwhile to sling mud like that. Chances are they implemented some feature in the Play store that FF mobile doesn't support. When a FF mobile user goes to the site and its broken who would they blame most likely? Google? or Firefox? Experience tells me they'd blame Google.
Stop using Hanlons razor as lead in to why someone isn't malicious when you aren't in a position to know one way or the other!
edit: I would appreciate a response along with the downvote.