http://wpn.wizards.com/sites/wpn/files/attachements/mtg_jar_18jul14_en.pdfThe Judging at Regular REL document has the following advice for "General Unwanted Behaviors" one of which is tardiness.
"Educating players who exhibit these behaviors should be your primary motivation as a judge. It can be useful to reinforce this education with more stern penalties should a player's unwanted behaviour continue, especially in cases where players are likely to upset others.
A player that is more than 10 minutes late to a match is considered to have forfeited the match and should be dropped at the end of round if he or she is still absent.
If you have warned a player who may be upsetting others and your warning has not curbed their behaviour, or if a player is being threatening or aggressive, these situations are Serious Problems. "
Does your FNM have an actual judge?
If they are 10 minutes late they should get a match loss (per the official guidelines), if they are less than 10 minutes late a game loss can be appropriate (probably after a warning for the first offense).
If your judge believes the player is purposely showing up late to force the match to only one game then a disqualification is appropriate.
[Edited 1 times, lastly by Pail42 on May 22, 2015]