knowing a male massage therapist who has found it difficult to establish himself, I can see how such a question can be almost too much..
However, there is scope for discussion...
For example, in traditional Ayurvedic massage, a woman will only be massaged by a female therapist and a man by a male one....it is done so that the client can completely relax with no ambiguity, self-consciousness,etc...
I have personally been massaged by male and female masseurs. I really enjoyed the massage by the man. Reason being very simple: big warm hands moulding my shoulders or reassuringly covering the back...On the other hand, I strongly felt the therapist was gay (I know this may be interpreted the wrong way by some readers but it is my feeling) and therefore felt the atmosphere was "neutral", so I felt less self-conscious and more relaxed.
However, a gay or heterosexual masseur stillimplies some limits for me, as the receiver: when I talked about being massaged on the chest (chest tighness), like I saw in a few books being practised, the male therapist went rapidly into a self-protection load of correctness-rubbish. I really needed the work on the chest and if lying breast bare (like I do with my male osteopath and there is no problem) or even wearing a bikini is a problem for him, then I feel men should massage men and women massage women....I know he did not know me and thought I might have been testing him, but this underlined the limits in a man-woman treatment. I will now go for a female one, especially that I could talk about more stuff (periods,etc).
As for a female therapist treating women only: what is the problem? If all men were (openly)bisexual and could fancy men as well as women, I have no doubt male therapists working as mobile masseurs would think twice before entering a male client's house...
Of course, being a woman does not mean one is peace-loving, gentle andbalanced. Let's just picture a saturday night in any (british) city centre and remember the eternal feminine essence....I have seen sober or drunk women attacking men (at home), even police men on saturday nights (just ask any taxi driver for top stories). women seem to become more aggressive these days...well, it is only my opinion. But each time a car nearly run over my feet it was...a woman! sometimes she would even make the finger gesture to me!
Well, all this has gone far beyond the initial question.
In short, no it is not sexist. It does imply of course that some men can be dangerous, and this is the sad reality. (but women are catching up!). Being a mobile therapist - not trying to alarm you - is a bit risky. Try to operate in a way where you can find out as much as possible from the client: family/partner/job/permanent address?/since how long...I doubt these are the usual question a therapist would ask, but I am just trying to think of what I would like to know myself if I was mobile.
And last...is asking for a female gynecologist or a female chaperon to be presentwhile a male one examines you sexist??