True and False simultaneously…
TRUE, only as far that Xojo is built for the x86 platform; which Raspberry Pi is not (ARM). FASLE in regards that x86 platforms can and will run on a Raspberry Pi (ARM). Therefore, Xojo will run on a Raspberry Pi which is running an x86 platform. Stating that something is impossible, and stating that you do not know how to do something are two entirely separate entities.
“Beware of false knowledge; it is more dangerous than ignorance.” - George Bernard Shaw
Here is a step-by-step video for those whom truly wish to install and use Xojo on a Raspberry Pi. With the advent of the latest RPi, Windows and x86 linux now run much better (more smoothly/responsive) in GUI mode. It is still recommended that your Xojo applications be compiled on a development machine, then transferred to the RPi for runtime. It will save you time with large pieces of software since RPi memory swapping to the SD-Card can turn a 30 second compilation into a 3+ minute compilation.
Nothing is impossible; the possibility merely exists outside one’s scope of consciousness. - me
How To Video:
Xojo loading on an RPi, from within the ReactOS environment

A debug-build Xojo application running on the RPi

I chose ReactOS for this demo because a Qemu image already exists for download, therefore no OS install/setup was necessary, and the entire process took about 5 minutes. Installing Windows/Linux require upwards of 30-45 minutes to install and setup.
***For Linux, there are also Qemu images available, I did not take the time to search for one, but they do exist.
If you have trouble, there are innumerable videos on how to run x86 applications on ARM (as well as other) processors, and many threads in the RPi and Qemu forums describing How-To’s (even accessing RPi GPIO from QEMU!) as well.
With LLVM, in the future, Xojo Inc. should be able to compile a native ARM version of Xojo. That though, remains unannounced.
Aside:
***Running x86 OS’s from Android devices (ARM processors using Limbo) has changed slightly since the release of KitKat 4.4.x, since SD-card permissions/access (for writing) have changed slightly. KitKat 4.4.x now requires a rooted Android device to restore full write-permissions to user-installed applications.