Kindness and decency includes being realistic and factual about expectations.
It is not realistic for this individual to expect or hope to be perceived as female.
It is quite realistic to expect to be able to live and interact with the world quite safely and openly with a trans identity and dressing and presenting in line with that. People really aren't that bothered mostly.
It's really difficult to get reliable disaggregated statistics when there have been so many years where the TRA lobby has been insisting that merely saying "male people cannot be female" is recorded as a hatred and people have had police visits for posting facts on twitteX - but in terms of safety the ordinary round of commuting, doing a job, doing the shopping and chores and all that, is perfectly safe. About 60% of victims of transphobic attacks are sex workers - which is not to say that such attacks are in any way acceptable or that the victims are to blame, but just that an individual who identifies as trans and is not planning to become a sex worker is probably a lot safer than they might otherwise be fearful of.
Your kindness can focus on helping build resilience - having the courage to go out into the world confidently claiming and embracing the right to reject gendered expectations is great. Expecting people to actually believe that someone who is clearly male is actually female is unrealistic, but there should be no shame in acknowledging and owning the fact of being a male who prefers to present according to feminine expectations. Resilience will include not letting the occasional sniggers get to you, they are part of the societal pressure towards gender conformity that created the whole realm of gendered division in the first place - if there were no sniggers, it would not be actually possible to be trans because there would be no expectations to reject.
The Equality Act enshrines a trans-identifying person's right not to be discriminated against and this is protection against less favourable treatment in employment, housing and access to services and opportunities. The FWS Supreme Court ruling confirmed this and upholds that trans identifying people have every right to exist and live their lives without fear. The clarification that was needed due to more than a decade of misinformation was just that the comparator for "less favourable treatment" is that a male who identifies as trans should not be in any worse a position than a male who does not identify as trans - rather than that they should have access to anything that is specifically for female people, whose rights to have female-only facilities and opportunities are also upheld and are not open to male people with a feminine gender identity any more than they are open to male people with any other kind of identity.