You "can" use a protected NCR/INR in a regulated mod, as long as it is accepting it without error codes or what not. It's not the ideal battery to use for your mod's optimal performance. Once you use low resistance atomizers or higher voltages which will begin to pull more amps from your battery, performance could become impaired or the battery might complain by becoming overheated. Protected batteries don't have the "high drain" load current capability that an IMR will have.
When those listings say "unprotected" battery, they DO NOT mean a un-protected NCR/ICR li-ion battery (these should never be used in a mod).
They mean a "high drain" IMR (li-mn or lithium manganese), also known as a "safe chemistry" and as a "unprotected battery".
These are used in regulated mods that use buck boost circuitry to achieve variable voltage-wattage, but they are now also recommended for single voltage mechanical mods as a safer alternative to protected Li Ion batteries.
This class will have less capacity in mAh rating compared to protected batteries, but are superior when maximum load current is required, such as in regulated mods, mechanical mods using a Kick, or using an RBA.
The newer "hybrid" batteries by Panasonic/Orbtronic, Sony, and Samsung also fit into this category. These are a good choice for applications that demand both maximum load current and longer battery time.
Below is a listing of IMR or hybrid batteries which are recommended for all applications. (Mechanical mods using extreme sub-ohm vaping require IMR or hybrid batteries with more than 10 amps of continuous discharge rate.)
18650 2000mah 10Amp CDR
18650 1600mah 24A
Samsung hybrid (LiNiCoMnP)
INR18650-22P 2200mAh 10A
INR18650-20R 2000mah 22A
18650 1500mah 20A
Panasonic or Orbtronic hybrid
CGR18650CH (IMR/hybrid) 2250mAh 10A
NCR18650PD (LiNiCoAl) 2900mAh 10A
18650 (IMR/hybrid) 2250mAh 10A
18650 2000mAh 10A
18650 1600mAh 30A
us18650v3 IMR 2250mAh 10A
us18650vct3 (hybrid) 1600mAh 30A
* AW IMR 18490 (1100mah) 8.8A
*AW IMR 18350 (700mah) 6A
**The Panasonic NCR18650B 3400mAh is not a high drain battery and only has a 6.8 amp limit.
Battery Basics for Mods: IMR or Protected?