I doubt that would happen. That USMLE would probably get you in the door. Also, most students perform better on the COMLEX in relation to the USMLE anyway. The only ones who don't are the ones that totally blow off OMM or just dislike it so much they can't learn it well.
I mean the reality is that there's like 6000 DO students now with a pre-med average MCAT of 27ish and there's about 20000 MD students with a pre-med average MCAT of 31ish including the top 20 schools which have an MCAT average of like 34-35. If you scoop up only about the top half of DO students (3185 took the USMLE step 1 in 2015) and add them with the MDs (20213 took Step 1 in 2015), you can see why it's harder to score a higher percentile on the USMLE than COMLEX. Really the only saving grace there is all those carib. people getting 200s and whatnot (not sure how many of them there are but there was 15030 non US/Canadian takers of Step 1 in 2015).
http://www.usmle.org/performance-data/default.aspx#2015_step-1
If you're a DO scoring 255+ (91st percentile+
http://www.usmle.org/pdfs/transcripts/USMLE_Step_Examination_Score_Interpretation_Guidelines.pdf), then that means you'd have been in the top 3787 students (42082 overall) and in the top 2190 students if you only consider US MD and DOs (2106 if considering only 1st time takers). The top 10 (US NEWS&WORLD REPORT) MD schools have about 1700 students per year in total with an average incoming MCAT of 36 and average incoming gpa of 3.85. The reality is that it's much harder as a DO to compete with and beat those students (and the rest of the US MDs) than it is to compete with and beat the DO students. Thus, usually a DO student has a higher percentile on COMLEX than USMLE. You can see why it's impressive when DOs score 255-260+ and even if a PD doesn't want a DO in their program, they usually will say complimentary things like "you really scored well and you should be proud. We would love to see that score from our own students. Sorry we can't take DOs."
As far as EM goes, it's the most notable specialty for this thread and discussion about COMLEX/USMLE scores because right now it's in that spot of moderately competitive for both MDs and DOs, average USMLE (230), above average COMLEX (~550-575), most programs will take/interview DOs, and many programs will look at people who have just COMLEX.