This comparison is flawed because there is not legal pickpocketing, but there is legal immigration.
If there was a legal pickpocketing, and someone claimed to only be opposed to illegal pickpocketing, then it would be reasonable to point out that unless they're lying about their intent a solution to preventing illegal pickpocketing would be to make it all legal.
The analogy falls apart because nobody argues that they are "only" opposed to illegal pickpicketing.
If people are opposed to any form of immigration, then they should just admit that, rather than pretend they're only opposed to illegal immigration.
If there was a legal pickpocketing, and someone claimed to only be opposed to illegal pickpocketing, then it would be reasonable to point out that unless they're lying about their intent a solution to preventing illegal pickpocketing would be to make it all legal.
The analogy falls apart because nobody argues that they are "only" opposed to illegal pickpicketing.
If people are opposed to any form of immigration, then they should just admit that, rather than pretend they're only opposed to illegal immigration.