We are not even sure whether there was an aircraft immediately ahead of 521 who had to clear the runway before Twr could issue landing clearance to 521.
ATC wasnt too busy to see something that caused them to issue climb instruction. Lets stop the ridiculous rebuttals shall we?
Portmanteau. Follow your own advice.
Dubai Tower doesn't always have to wait for the aircraft to clear the runway before giving clearance to land to the following aircraft. At times when Local Reduced Separation procedures are in force this is what occurs. I don't know if they were at the time, or not.
Likewise, you don't know whether the Tower instructions for the missed approach were given in response to EK521 informing them that they were conducting a missed approach. The transmission are clipped, and not all have been caught.