Bolt heads strip out with very little torque if there is not enough downward pressure on the tool, basic mechanics. Our shop has literally hundreds of bolts with stripped out heads that have NEVER seen any loc-tite. I wouldn't assume that the board has been loc-tited, no reputable shop would ever do that for multiple reasons. I agree with what was posted previously that if they did use loc-tite don't ever let that shop touch your equipment again. Any shop with kids stupid enough to use loc-tite probably has a problem with repair/tech work in general.
Heat is not your board's friend and should be avoided at ALL COSTS. As was stated above it takes around 500 degrees to break down red loc-tite, epoxy also breaks down at these temperatures. Epoxy resin holds your board together and helps keep your inserts from spinning. Not to mention the fact that heating the screw will damage the disc holding the binding to the board.
Impact drivers aren't really that much better of a solution. Too much torque on the seized peices can work the inserts loose and allow them to spin. Be carefull with using a hammer also. The downward force can easily break the epoxy loose and allow spinning or worse it could push the entire assembly through the core and bubble the base. Ignore what a gunsmith tells you, he is working with components much stronger and resilient than the wood and epoxy core of your typical snowboard. In the battle between wood and metal, metal wins every time.
First advice, take it to a shop that knows what the heck they doing. If you are the DIY type, doubtfull as you let someone else set up your board already, slot the head with a dremel or use an easy out kit. If the screw head still strips out at that point then cut away the discs and get the binding off the board, discs are the cheapest part of your set-up to replace. Once the bolts are exposed you will be able to tell if the shop used loc-tite. If there is no loc-tite the bolt should turn out fairly easily.