I don't think it is that simple. The "Conditional PTC" is not even addressed in the body of the rules, but rather in the footnote:
"10A 7.37 INCREMENTAL IFT: The Incremental IFT and its accompanying article ("One-Half FP") first appeared in the ASL Annual '89. (In 1998, both were reprinted in Classic ASL.) Thereafter, various commentaries appeared in several succeeding Annuals. At one time, the ASL community seemed seriously divided over whether the IIFT should either be declared the official IFT or should be relegated to the dustbin. Since that time, however, consensus has settled upon treating the IIFT as just another option rule, and that is how we present it here in the 2nd edition."
"One of the several criticisms leveled against the IIFT was that, by adding additional PTC effects for higher Final DRs in the various intermediate FP columns, the IIFT strips concealment more readily than does the regular IFT. To counter this criticism, some suggested making all those additional PTC effects conditional, so that they only applied to unconcealed units and thus would not strip concealment too easily. We tend to agree with this thinking, and seriously considered changing the IIFT in that manner. In the end, however, we decided to leave the IIFT essentially unchanged from when it was originally published in 1989, but highlighted such "conditional" PTCs on the IIFT in blue. Anyone concerned about concealment being stripped away too easily can adopt the "conditional" PTC as a house rule."
The bold is my emphasis. The reasoning is clearly given as a way to prevent easier concealment stripping, however, the bolded text says they only apply to unconcealed units. So you have multiple choices - a) you use the IIFT without CTC, A7.37 indicates, b) you use CTC per the footnote (and they don't apply at all against concealed units, or c) you use CTC and they do apply against concealed units for everything except concealment loss.
IMO, if you use them, you should be going with choice b), however, use of them is optional, just like use of the IIFT, so it is up to the players to decide between themselves. The reasoning behind not applying them at all to concealed units would be that any/all TC's, not just concealment loss, are increased by their introduction, so if you are concerned about how concealed units are affected, you might as well include all effects.
