hmc, it might be hard for dyslexics to learn by rote in terms of verbally reciting the tables, but there are other ways that still lead to knowing them by heart. There was a discussion of this on another thread just the other day, so I won't repeat what I said there, but it's easy for people to assume that 'instant recall' means being able to recite them aloud, but it doesn't. If you google things like 'visual memory' and times tables, or 'multisensory' and times tables, you will find lists of methods that are very helpful for people without good verbal memory, including visual methods, finger tricks, and so on. If you can visualise answers, that's as immediate access as being able to say them.
It's also possible to work on rapid recall, timed tests, flash cards, repetitive games, etc, without humiliating dyslexic children - it doesn't have to be done in public, or in a competitive way.
If all else fails, a printed table square that a child can easily access can be very useful - sometimes it is easier just to get the answer and then get on with solving the problem or understanding the concept being taught, than to try to work out an answer by using one of the counting out methods, or one of the calculating methods, because those can depend so heavily on sequencing skills. Some dyslexic children are fine with that, especially if they have a good understanding of maths, but others can find the number of steps, and the numnber of extra numbers that they have to 'hold' in their heads, very confusing.