The commission would give them the .9 allowance. This could be standard in Montreal and just something nobody mentioned to Diaz's camp. (but something they should have looked into). Different commissions can have slightly different rules, looking at past title fights in Montreal, Thales Leites weighed in at 185 so what are the odds there was no decimal place, GSP weighted 170 against Condit and Koscheck.
And since 2008 None of the weigh ins in Montreal show a decimal in the results. Nobody weighs in at 169.5? Everybody is a round number so to me I think its something that has been in place a long time and yes something GSP was likely aware of already having fought in Montreal previously. While it may have been unfair to Nick at least partial blame could be put on the Diaz camp for not making sure they knew any minor changes instituted by the local commission. Its unair but not malicious.
"If you get hit and it hurts hit him back you not knocked out yet."-Joe Doerksen
The Toxic Terrors (FFL)
Demetrious Johnson*Eduardo Dantas*Rafael Silva*Zach Makovsky*Michael Page