Not to go "high road" on anybody, but if you do that, here is likely what will happen...
1. Nobody in that unit will get hired down the road. Legal or not--hard to prove with a tough interview that the reason he/she got turned down was a bunch of guys from that unit burned the company. My unscientific opinion is there are a few units with a "bad name" out there and guys have a harder time getting hired from them. This isn't' FDX specific...it applies to most majors.
2. Proabation will get extended. Again--for the individual--I don't think that's a big deal. I don't know of any probies who've been canned for trivial stuff.
An alternative might be to go to Paris/Hong Kong, but drop two weeks every two months--say the last week of one month and the first week of the next. FDX gets you 3/4 weeks--which should be reasonable, and you commute once to your unit for two weeks solid of work....the classic "week a month" deal. Might not work in high tempo squadrons or special ops jobs, but for the guys doing the training gig it might just work. You'll be a hero to your unit for bringing in French wine, and a hero to your FDA bros for bringing over BBQ.
Having done both jobs, I can say even living in your ANG base flying two jets and doing two jobs is tough. However, if you could roll in for 2 weeks straight away from family in the land of the big BX, then RTB to your FDA, you could probably keep both your bosses generally happy. I took some heat a few years back asking for some leave over Christmas (it was legit--I was behind on sorties after just completeing 727 FO training) but right now I think manning across the board is fairly fat. I cannot imagine with the importance of getting the FDAs launched effectively that they will min man them so the point any changes might affect reliability. Perhaps one of our Subic folks can give us some insight into the relative manning at an existing FDA.