Perhaps "heresy" is too strong a word, Matthew. That word is thrown around on all sides way too casually.
If he believes that sensible pleasure is intrinsically evil, well then yes he would be a Manichaeen / gnostic type. If, however, he's speaking to the fact that in our fallen state it's nearly impossible without taking such measures to subordinate the sensible pleasure to the intellect and the will, then he would be correct. Church Fathers would have characterized the insubordination of sensible pleasure over the will and intellect as a venial sin. At the very least it's an imperfection that can harm the soul. That's why even St. Paul says that virginity is ideal but that it's better to be married than to burn. Our Lord said that there would be no marriage in heaven, that we would become like the angels.
So it would depend on what AllMonks (or his predecessor screen name) would have meant by these statements.
It's a bit disturbing that you seem to be on "his side". I didn't read all of his voluminous posts, nevermind the dozen threads he posted in, but if I'm not mistaken you were siding with him.
Having a puritan view of sex is *not* Catholic. Sex is good, holy, and beautiful. It's not for public consumption because it's sacred, not because it's dirty. It was designed by God, along with the pleasure and consequent chemically-induced psychological and emotional bonding that accompanies it. That's why the devil strives so fiercely to corrupt it. It's the easiest way to gain souls for hell. Bad marriages, bad companions, bad habits, broken families, lack of Catholic training, bad example, etc. More souls go to hell because of sins of the flesh, etc.
When a man starts distorting doctrine in ANY direction, the only Catholic response is revulsion. Therefore I have revulsion re: Heitanen's views. You seem to be interested in his views and have thought about them deeply, to the point that you agree with him (!)
You know, there is a pretty strong pleasure attached to eating, too. But no one claims it's a sin to eat delicious food (rather than bland or even disgusting food), nor does anyone say we must eat only plain dry bread OR WE'RE GOING TO HELL. Or that if you can't scrape all the flavor off your food, you must sprinkle it with bitter herbs and hold your nose while eating it. But that's precisely Heitanen's view on sex.
It's as wrong and perverted as the hedonists -- just in the opposite direction.
Both are repulsive to anyone with a well-formed Catholic sense.