He is argument boils down to, some languages have four (or more) sets of pronouns: male, female, single and/or plural of people that is genderless (either explicitly or implicitly), singular and/or plural of inanimate object(s).
English has male, female, plural of people that is explicitly genderless (but not singular), and singular only of inanimate objects (but not plural). We don't have a pronoun that can fit a singular third gender or genderless reference. Using they as a singular pronoun in any situation often leads to awkward speech.
Other languages do other things, such as inanimate objects often being referred to with male or female pronouns (independent of having a singular inanimate pronouns), having both singular and plural inanimate object pronouns, or having singular genderless pronouns.
Adding additional words to English may be required to deal with people who do not wish to use male or female pronouns, but also do not wish to be called an it, or be forced to be called a they inappropriately (since they are not a plural, nor a royal we). Such words should appear similar to regular words, such words should be also standardized and regulated.
/End of RMS boiling down: at no point does he say trans people don't deserve pronouns that can fit their needs, he only illustrates that how we handle it now is not a good solution.