This is a variant of the venerable security through obscurity.
Not really.
Security is not an all-or-nothing proposition. In the real world, an adversary will NOT attempt to crack your encrypted filesystem. Instead they will do one of a hundred other attacks, like swapping your laptop with one that has a cloned disk and hardware but an embedded keylogger, or add in a shim between the disk and interface, or install an infected MBR that logs the decryption password, or perform a RAM sniffing attack to steal the keys, or simply extort the keys out of you.
Security is a process of analyzing the most common risks, and determining the best way to deal with them. Sometimes this means determining that a particular security action will lower your security by attracting the attention of entities with far more sophistication than you are prepared to deal with; if you are worried about criminals stealing your laptop, and your mitigation ends up attracting the attention of the NSA, you have lost the security battle.
IDS / antivirus have no ability whatsoever to detect a hardware keylogger, by the way. If you attract the attention of someone who can gain physical access to your hardware, you lose-- period.