elections were being scheduled...
The EU does not, contrary to some opinion, have the power to set in stone, any conditions on what member states must do to alter lengths of governmental term in office. That would be interference in a sovereign state's rule and simply put, would not stand.
Like in America - the government agrees to govern for 4 years, unless there is a vote of no confidence. Her majesty's opposition have every confidence in Johnson making a complete dick of himself, so they are not going to let him off the hook now. The longer this government goes on for, the deeper the hole they dig for themselves. The EU simply gave the UK the time to work out for themselves that it is time to put the question of EU membership back to the people.
Johnson can have a December 9th election, but he doesn't want that, because:
1. Students will still be registered to vote at their colleges
2. Xmas postal ballots will be more likely to actually be counted
3 He knows he wont get a 12th date becasue of 1 and 2 and wants to blame his defeat on the "enemy of the poeple - that chicken..."