I think context is important. It is good to outline why they need to be up to speed quickly.
If someone has the need for a senior frontend engineer to contribute immediately on a complex frontend app where they are directly replacing a key engineer who left, then what you said makes a lot of sense. Lots of stakeholders are likely to nervous about bringing in a solid developer who isn't already working in the discipline. Often there can be fall out in organizations from this that results in the support systems failing for the hire which compounds problems for them.
When you are thinking about the long-term health of your organization though it is useful to support people in making this transition. Why would they want to stay with your organization long-term if they can't make these kind of changes? They can likely do some frontend projects on the side and go somewhere else combining a salary bump and a discipline change.
Ultimately, you can't guarantee these opportunities for anyone, but it's a case of appearing to be reasonable. That's not the feeling you probably wanted to convey, but it's what came across.
If someone has the need for a senior frontend engineer to contribute immediately on a complex frontend app where they are directly replacing a key engineer who left, then what you said makes a lot of sense. Lots of stakeholders are likely to nervous about bringing in a solid developer who isn't already working in the discipline. Often there can be fall out in organizations from this that results in the support systems failing for the hire which compounds problems for them.
When you are thinking about the long-term health of your organization though it is useful to support people in making this transition. Why would they want to stay with your organization long-term if they can't make these kind of changes? They can likely do some frontend projects on the side and go somewhere else combining a salary bump and a discipline change.
Ultimately, you can't guarantee these opportunities for anyone, but it's a case of appearing to be reasonable. That's not the feeling you probably wanted to convey, but it's what came across.