I think he is really warning that Q1-20 will simply be tough for both revenue and loss.
Unlike legacy automobile manufacturers, Tesla can't stuff inventory into the dealer channel and take revenue on unsold vehicles. Since people in North America and Europe tend not to buy cars in January and February, sales will take a dip.
Sad and frustrating that analysts and business press are too lazy, stupid and/or biased to take this unique to Tesla quarterly reporting situation into account. Hopefully if M3 + MY become production constrained after ramping up, there will be a year or two where quarterly sales will even out until production again catches up with demand. After that the volume of production and revenue from that volume will make lower Q1 sales irrelevant.