I realised that and, since it appears that it wasn't obvious that I did, I suppose I should have added a smilie!It's humour, John.
Indeed, and I didn't suggest that it was 'disallowed'. I was merely pointing out that your (I thought 'obviously') tongue-in-cheek comment reinforced what I had previously written.That you have said it before does not disallow anyone saying it or commenting on it again.
However, to be a bit more serious it is clearly worrying that, now that "flammable" has come into quite common use, there will be people who are 'confused' into thinking that "inflammable" is the opposite. One can argue that such is because they are inadequately educated, etymologically-aware, just "plain incorrect" or whatever, but that doesn't alter the fact that their misunderstanding could present dangers to them. It therefore would seem advisable that we should do all we can to minimise/eliminate use of one of the words = and, in view opf the way things have evolved, I suppose it is probably "inflammable" that 'needs to go'!
I would add that I'm not sure that I can blame these 'uneducated' people all that much. I've been trying hard, but I haven't yet thought of any other adjective for which there is a corresponding one with an "in" prefix added for which that "in" does not indicate negation.
Kind Regards, John