I have progressively grown cynical about all people who insist on showing off their faith, whichever it is, as all of them have proven to be much less pious when no one was looking.
Regarding muslims, I have worked with many, and honestly got a bit tired of hearing how great Allah is, and having to walk around their prayer mats in offices, and a couple of hours later seeing them drinking beer ("as beer does not really make you drunk, and as such is not forbidden", yeah right) and having to drive one of them out of the city once so he could have a sandwich during Ramadan ("the Koran says that if you're a traveller you can skip the fasting", and of course, me taking him out of the city automatically classified him as "a traveller").
I also had to listen to how their wives had to be pure and chaste while they could sleep around as much as they wanted, provided they signed a "24-hour-marriage certificate" and "divorced" the woman at the end of the day.
I am sure Allah will love to hear of how easily He was fooled when all these people get to see him face to face.
So yes, I would be annoyed at having to jump over a praying Muslim in my office and not being able to access the phone/fart/do my work in peace. If he wants to take time off work to do anything (be it pray, smoke, or practice juggling) he can go outside to do it. Surely the sacrifice of praying out in the cold would just add to his image before Allah?