Let's look at what was actually said by Pollock in the article cited. (The bolding is mine, and the parts in red are my comments.)
Getting into a hot tub immediately after diving does alter decompression stress. As with many factors, the net response can be positive or negative, depending on the magnitude of the inert gas load and the heat stress. The hot tub or hot shower will warm the extremities and enhance peripheral circulation which might facilitate inert gas washout (or inert gas elimination). Sounds good! Get in the tub!
Large inert gas loads, however, can be problematic. Since the solubility of gas is inversely related to temperature, tissues will hold less in solution as they warm. Warming tissue with significant gas loads can promote bubble formation. Since the warming of the superficial tissues precedes the increase in blood flow, such bubbles can pose problems before the increased circulation can remove them. There is no simple formula to compute what constitutes a minor, significant or substantial peripheral inert gas load. The actual conditions vary as a function of the individual, thermal protection, physical activity and dive profile. So, if we have a significant gas load (nearly bent?), it is theoretically possible that it could create bubbles.
My approach is to stack as many factors as possible in my favor to compensate for the Murphy effect we frequently see in decompression sickness. I encourage a simple rule of thumb: delayed gratification. Enjoy the thought of the hot tub or shower for a while instead of jumping in immediately. An interval of 15 to 30 minutes should help you avoid some of the risk, as will keeping more conservative dive profiles. Another compromise would be to employ a lower temperature in the hot tub or shower.Ah, so to play it safe, we should wait 15-30 minutes after diving before getting in the hot tub. I usually have no trouble getting my gear off, getting to a hot tub, and immersing myself within 2-3 minutes, so this will be a major inconvenience, no doubt, but maybe I can handle that much of a delay if I really, really control myself.
When I read this, I have trouble seeing how people are reading this as a warning against going into hot tubs after diving. When I read it, I feel encouraged to go ahead.
