As for George Will's rectal mucosa theory of AIDS {op-ed, June 7}: it is appalling to see a columnist's speculations elevated to the realm of fact, especially when there is at least as much evidence against his contention that there is something so special about the actual practices of homosexuality as to ensure that the predominant reservoir of the disease will remain with homosexuals. Mr. Will's column does a disservice in two major (and I'm sure, many minor) ways:

1) The implication is that heterosexuals may heave a collective sigh of relief and pursue their sexual activities with somewhat less trepidation.

2) There is now the likelihood that the heterosexual majority will be less keen to support research for a disease that is confined to a rather unpopular minority.

Reports from Africa suggest that AIDS has already become a heterosexual disease of frightening proportions. Physicians like myself realize we function in an area of impressive ignorance. We can only advise what seems prudent, realizing our advice may change as research provides more answers.

Mr. Will risks moving from a position of renowned conservatism to one of medieval reaction by suggesting, however obliquely, that this plague has been visited upon those who in some way deserve it. There will always be ''innocent'' victims of disease. And I would argue that patients should always be considered ''innocent'' and treated with compassion.

What the world needs now is a biologist who can provide the kind of relief Jonas Salk provided from polio. Perhaps his name will be Anthony Fauci, perhaps we have not yet heard his name. But I very much doubt that relief will come from the speculations of George Will.

NEIL RAVIN

Chevy Chase