If you are speaking of standard non hardened construction grade steel galvanized all thread then
ABSOLUTELY NOT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I have used threaded rod for over 20 years in sizes from 1/4" up to 2" and literally thousands of feet of 1/4", 3/8" and 1/2" treaded rod and every thread structurally weakens the rod significantly to any flexure and shear forces when applied to the threaded rod.
Threaded rod is meant by design to withstand tension forces or forces that pull mostly straight down or straight up and are very poorly suited to and not designed or intended to withstand shearing forces caused as a result of side pressure or flexing. This fact is absolutely true of a single section of threaded rod, granted multiple threaded rods when installed in conjunction with each other in an application of mutual support of an object can withstand shearing or flexing forces rather well but individual stand alone sections of rod are very week and prone to failure when subjected to shearing or flexing forces. The chances of a single section of threaded rod failing under side pressure or flexing is at its greatest when a length of the rod is supported and can not being subjected to side pressure or flexing and the unsupported length of rod is subjected to side pressure or flexing. A perfect example is when I would use a drop in anchor to anchor a 1/2" piece of threaded rod into a concrete ceiling to act as one of several supports of a extremely heavy pipe run or piece of very large and heavy equipment equipment like a transformer weighing from 500-2000lbs. Used in such a application where the rod is usually only exposed to pulling forces as created by gravity even 1/4 threaded rid is immensely strong, but even a single 1/2" threaded rod secured in this manner that easily will withstand thousands of pounds of tensional, pulling or downward force will quite easily snap in two when subjected to very little shear force, as an example a decently strong man using only his hands could easily snap off a 12" long section of 1/2" threaded rod secured to a concrete ceiling while standing on a ladder when that same rod could easily support a hanging 305ci V8 engine.
And keep this last fact in mind. When threaded rod snaps off it almost always leaves a sharp edge, sharp hooked burr or both on one or both halves, and one halve that WILL have a sharp edge will still be in the tree awaiting various parts of your bodies impending very hard gravity driven contact with it.
In my experienced based opinion using threaded rod as a tree bolt, you are risking at the vary minimum being very seriously injured, quite possible permanently, and life altering possibly fatally injured, as you will not only be dealing with injuries from the impact trauma of falling but also from more likely than not the very significant chance of suffering a very serious laceration and the equally serious bleeding that results.
Stick with high quality certified made in USA grade 8 bolts for climbing trees. You well being is well worth the minimal cost to do so.